


Deep Below

by orphan_account



Category: Sherlock (TV)
Genre: Alternate Universe, Alternate Universe - Historical, BAMF John, Eventual Happy Ending, Fluff and Angst, Historical, John Has a Beard, Jules Verne has a lot to answer for, M/M, Merman John, Minor Character Death, Ocean, Pining, Sherlock's First Time, Submarines, Underwater Sex, Very Minor, Virgin Sherlock, sherlock is a small nerd, technically
Language: English
Status: In-Progress
Published: 2016-05-13
Updated: 2016-06-04
Packaged: 2018-06-07 11:42:14
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 22,181
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6802315
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: <blockquote class="userstuff">
              <p>Professor Sherlock Holmes is in search of a mysterious sea creature when he is thrown overboard and lands in a world where everything is strange and new. The sea monster he seeks is actually a technological marvel-- a submarine crewed by men who have abandoned the laws of land-dwellers years ago. Yet though he is surrounded by undiscovered sea life and underwater treasures, the most valuable treasure Sherlock discovers is the creator of the submarine: Captain John Watson.</p>
            </blockquote>





	1. A Fearful Sight

**Notes for the Chapter:**

> A retelling of 20,000 Leagues Under the Sea. You do not have to read that story to understand this one. Enjoy!

Sherlock woke to shouts of horror on deck. For several moments he lay in his cot, his head throbbing with the sway of the ship and his mind jostled by interrupted sleep. He sat up and fumbled about with his clothes before realising what was going on. _Oh!_ _Of course!_ A wide grin spread across his face, as he shoved on a pair of trousers. His movements were much more hurried after that.

Sherlock stormed up the stairs to the top deck, stuffing all his assorted journals and pens into his waterproof case, keeping only a small sketchbook and pen out for him to capture the likeness of the rumoured beast. The _HMS Victoria_ and her bounty-hunting crew had spent the past month and a half ruthlessly combing the North Atlantic waters for the sea monster that had been attacking and puncturing the hulls of ships of both the British and French navy. If the crew had at long last found whatever the troublemaker of the seas was, Sherlock was going to be there to record every detail of it. He had specifically requested to the captain that should they kill or maim the beast, they would drag it on board if possible, or at least pull it as close to the side of the ship to allow him further scientific measurements and evidence.

“Professor Holmes!” a voice shouted above the howling winds as he reached the deck. Sherlock swivelled around to identify the voice and found the captain of the ship hurriedly motioning him to the railing, pointing with his other hand down into the waters. Sherlock skidded across to him, eagerly ignoring every word the captain said as his eyes scanned the roiling depths below in search of what the crew had spotted.

There, just a glimpse, hard to see against the pounding rain, was an eerie glow radiating from beneath the surface. He leaned over as far as was safe to get a better look, but the light suddenly disappeared, leaving only what to an untrained eye would be open ocean.

“It was Anderson.”

“Hmm?” Sherlock straightened up, just now paying attention to the captain, who was standing uncomfortably close to him.

“It was Anderson that spotted it. About an hour ago, but it only started glowing a few minutes before you arrived. Don’t worry Professor Holmes!” he grinned and clasped Sherlock’s arm, “We’ll get your _giant narwhal_ for you.”

Most of the men who had gone on this journey found Sherlock’s hypothesis to be laughable at best. Everyone knew the largest sea creature was a whale, so why might it not be a whale? That was certainly what Anderson, the harpooner chosen for the hunt, believed. Sherlock spotted the man in question rushing back and forth across the deck, slipping and sliding about with his terrible harpoon in hand and a delighted grin on his face.

Sherlock still held that the round punctures that caused ships to sink where the perfect size for a giant narwhal, if the depths allowed for such a beast. Still, he would discover first hand if his hypothesis was correct, perhaps in only another hour or two, if the captain’s assurances and Anderson’s boasts were anything to go by.

Another chorus of cheers and shouts resounded from the other side of the ship as men gathered to look at an even stronger glow that was shining so brightly even Sherlock could see it from where he was standing. A chill rushed down his back, and he clutched his sketchbook closer, deciding to stuff it in his case as he wouldn’t be needing it any time soon. If the beast kept appearing and disappearing, with only an otherworldly light to announce its presence, it would take a while for them to catch it. The ruckus died down once the lights had vanished again, and for several minutes it seemed there would be no more signs of where the monster was.

Suddenly, the ship shuddered and there were screams from below deck. Sherlock gripped onto the railing as tight as he could as the ship began to lean to the side, ropes and barrels almost crashing into him as he tried to avoid the debris. Looking down, the great maw of the sea opened up before him, wave after wave spraying up and assaulting his body. It was as if he was staring into the very heart of the sea. Beneath him he saw, for just a moment, a long, cylindrical shape glowing like the fires of hell, lighting up the waters around it. All of Sherlock’s previous thoughts ground to a halt as he gawked in awe of what he beheld. This was no sea monster of any natural design. It was a steel-encased machination that could only have been created by man, and it was terrible, and it was definitely not a giant narwhal.

The _HMS Victoria_ shuddered again and an icy cold wave roared up onto the deck, breaking Sherlock’s grip from the railing before he had a chance to understand what was going on. As if in a dream, he watched his body tumble down towards the howling abyss. It was almost peaceful, gliding through the air. Then he dove head-first into the water, crashing against something hard, and then there was no more.

\-------------

There was no movement. No light. Barely any noise, except for the peculiar thudding coming from both sides of wherever he was. Sherlock lay on his back on a cold, hard surface and stared up at nothing. Had he truly died? After years of studying the sea, had that been what took him in the end? He scoffed, then his mood soured. He had heard many tales as a child of burning hellfire and searing flames, but if this was his fate it was truly a cruel act to make his eternal resting place one of sheer boredom and utter stagnation.

At the sound of his scoff something moved in the dark to the _left? right?_ of him.

“Where are you? Speak, foul demon!” Anderson shouted.

“While I grant you your guess is not far from the truth, I assure you we are both mortals stuck in this afterlife together.”

“I think I’d rather share this darkness with a demon.” the whaler grumbled.

Just then, a door opened and the room flashed into focus as a beam of light poured in. Sherlock and Anderson both winced, shielding their eyes, but after a few seconds Sherlock lowered his hand and looked up, just as two men entered the cell they had apparently been locked in.

The first man was about as tall as Sherlock and had strong shoulders and a defined jawline. His uniform further exaggerated him to appear formidable and commanding. He was sharply dressed, neat, and had silvery grey hair. When he entered the room, Anderson sat up with obvious intent to speak to this man as the captain. Yet something about him didn’t quite suggest leader; more like loyal assistant. Second in command perhaps?

Then the second man stepped in and Sherlock forgot wherever that line of thought was going. His brain instantly rushed through a flurry of deductions. _Military man, no tan, has been in charge for at least two… no three years, short but firm, compact but with a slightly muscular build, nicely dressed but doesn’t put much regard into appearances, unassuming, definitely a leader._

This was most certainly the captain of whatever ship they were in.

Before either of their prisoners could speak, the two men whispered to each other, and in a language which sounded vaguely bizarre yet somehow familiar. It was the type of familiarity of a language which he had never heard before, but it sounded so nice that he wished he knew it anyway.

“Excuse me, sirs?” Anderson spoke up, and the men quieted but did not give any appearance of understanding him. Anderson continued on, becoming increasingly nervous at their blank stares, “I’m afraid neither of us understand your language, but… emm…” He looked to Sherlock for help, and Sherlock sighed, standing up to face the men.

He said a few greetings in French, looking for any sign of recognition, and gave a brief overview of how they had been on a ship seeking out a sea monster troubling international waters. He cited his reasons as purely scientific interest, while generally avoiding stating anything about Anderson being a very eager, very dedicated harpooner. His story grounded to a halt when the last of his memories fell into place. What had he seen in those waters, just before he fell overboard? But… it couldn’t be…

Anderson spoke up again when Sherlock faltered. He had known enough of Sherlock on the previous ship’s voyage that whenever Sherlock got that puzzled, almost trance-like look on his face it meant he wouldn’t be talking for at least the next couple of minutes. So instead he tried explaining their situation in broken German, but again neither men showed any sign of comprehension. At last he gave up and shuffled back to the corner of the cell, mumbling to himself and cursing his fate.

Just as he had finished, Sherlock’s eyes blinked rapidly and a wide grin of elation overtook his face. He clasped his hands together, “Ah, yes! I have it now, we are underwater! Just before I fell off the _Victoria_ I saw a large metal tube swimming through the water. And are we not surrounded by metal now even as we speak.” He grinned, turning towards the strange men, who still looked at him with little interest. He pointed at the taller man, “Chief Officer. Second in command.” He then pointed at the other, “And I believe this is the captain of this fantastically impossible vessel!”

“But how can that be? Where are we?” Anderson scratched his head.

He asked a few more tedious questions, but Sherlock wasn’t listening. He had been wading in and out of his own mind palace, gathering information from his memories and storing them in a new room he had built specifically for this… whatever it was. But then a motion caught his eye, and he looked over to see the captain staring back at him. Something had changed. Up until this point the man’s face had remained neutral, but with the sight of Sherlock bouncing about making deductions, a faint glimmer of recognition slipped through his mask. Sherlock grinned but decided to keep this little fact tucked away to himself.

He spoke up again, “It’s quite a shame these men cannot understand us or I should ask them if we may explore such an amazing creation. The engineering for this machine must be several years ahead of anything we have seen on land.” Sherlock said in his deepest, warmest tone of voice, glancing at the captain to see if his words had any effect. Judging by the barest hint of a smile, it had.

The two men then left without another word, shutting the door and leaving their prisoners in the dark, perhaps to discuss what would be done with their new captives. Anderson groaned but Sherlock smiled, content that he had at least briefly connected in a meaningful way. He could only hope now that the men’s decision would be a merciful one, and they would be allowed to get off at the nearest dock possible with little consequence to either party.

\------------

It was several hours (or at least it felt like it) before the door opened again. This time however, two of the crew came in and dragged Sherlock and Anderson out into the light, pushing them down hallways and through doors before either of them could get a proper look at their surroundings. When they finally were able to see again, they were both sitting in the captain’s office in front of his desk, and the captain stood behind his chair, back rigidly straight and fists held tight at his sides.

The room was silent for many moments. Then the captain sighed and his posture eased.

He cleared his throat, “I hope our first meeting did not startle you or make you feel threatened. We did not know who you were at first, only that you fell off the ship that tried to destroy us. You must surely understand then that we would need time to come to an informed decision.”

“Wait, you understand English… all this time?” Anderson sputtered

“I speak English, French, and German fluently. However, I command an international crew, all of whom shared no common language before boarding.”

“So you invented a new one for them?” Sherlock asked.

The captain hesitated, “In a way, though I must confess I used a simplified language from my homeland and tweaked it to my needs. The men still speak to their comrades in their native languages. We are quite a multilingual group here, so you should not fear speaking whatever language you feel most comfortable with to my men.”

“And just how long will we have to spend with your lovely crew in this metal contraption?” Anderson gritted his teeth. Sherlock would have perhaps taken a more civil approach to asking for their freedom, but there was little use pretending Anderson’s words hadn’t meant exactly what he himself was wondering.

The captain straightened up, glaring back at Anderson with equal force, “Your stay on my ship is indefinite.” He glanced at Sherlock with an odd look in his eyes, “I’m truly sorry, but I cannot allow the truth of my submarine to reach land. If any of my men or myself were to step back onto solid ground we would be instantly tried several years labor, or in some countries, certain death. You must understand that I cannot risk the safety of my men on the word of your honour.”

“This is madness! You cannot keep us here indefinitely without charges or evidence!” Anderson said.

Any kindness that had been in the captain’s eyes instantly fled, “Do not speak to me of supposed rights you may have. I am well aware of the justice systems on land, but here on my ship we have our own set of laws and follow none which were created by civilisation. As a prisoner of this ship you cannot leave to go to shore nor may you in any way spread news of our existence.”

Sherlock spoke up before Anderson could reply, “I am afraid, sir, that your presence is already known to the general public of both Britain and France, and perhaps several other nations. Your submarine has sunk or caused injury to multiple ships and I doubt they would let these acts go unpunished.”

“Which was why your ship was hunting me down?”

Sherlock winced, “I confess that is true, though I myself---”

“I heard your story, Professor Holmes, I am well aware of who you are.”

Sherlock looked up, “You… you are? How?”

The captain relaxed, settling into a more comfortable position. He gave Sherlock a faint smile, reaching behind him to pick out a small book from his stuffed shelf. It had been read many times, earmarked and bookmarked, and only a faint layer of dust graced its binding. When the man turned the cover towards him, Sherlock gave a startled laugh. It was titled “The Depths of the Sea”, and his name was printed in small lettering at the bottom. He had written that study a few years back when he was still attending university, but obviously his knowledge of the ocean had expanded since then.

“I was unaware you paid attention to awkward ramblings of my youth, sir.”

“No, not at all, it’s quite good.” he handed the book to Sherlock. When he opened it and flipped through, he saw numerous notes and markings, correcting what he had at the time believed to be scientifically-sound data. Apparently not. He raised an eyebrow at the captain and the man chuckled, scratching his beard.

“It is admirable for someone who has only been on land before. I obviously have more experiential knowledge of the ocean than you.”

“Obviously.”

Anderson sighed but said nothing, reclining further in his seat and taking the moment to look at all the bizarre things in the office. Most of it was aquatic-themed of course, although he noticed a portrait of a woman and her child sitting on the desk. He pointed, “Is that your wife?”

The captain startled for a moment but then shook his head, “No, no that would be my sister and her little boy.” He addressed both of them again, “And I’m afraid I’ve failed to introduce myself. I am Captain John Watson, and the vessel you are currently sitting in is a submarine of my own design and creation… The _Casse-cou_.”

Sherlock smirked. He knew French well enough to understand the ship’s name. _Daredevil. Thrill seeker_. What might that say about the captain of said vessel?

“What are the terms to be for our stay on board?” Sherlock asked in the politest manner he could.

“You may move freely about the submarine as you please. I believe, Mr. Holmes, you will be quite pleased at the vast knowledge I have acquired inside my library.” he glanced at Anderson, “I do not know you so well, but my Chief Officer Lestrade recognised the tattoos on your arm so we knew you were some form of sailor, long time in service. Judging by the story you reported you are also an experienced harpooner. Am I correct?”

Anderson’s mood lightened a bit, even if it was mostly due to surprise. He simply nodded. Sherlock on the other hand felt like an entire avalanche of question were ready to fall out of his mouth. He had been staring at Watson the entire time and had not seen the man retreat into any form of memory technique. He did not see the same look of keen observation and deduction that was evident in his older brother Mycroft’s face when they were younger and he was teaching Sherlock how to lift the very intimacies of a person’s life from their fingers and frown lines. Perhaps this captain was far more than he appeared to be.

“So… what, no standard issue uniform? I don’t have to wear one of your… actually what are you wearing?” Anderson pointed out.

Watson looked down as if he had just remembered he was wearing clothes, “The main fabric is my uniform from my time in the army. Lestrade has a similar uniform from the navy. They have kept in good condition for these past few years, but alas, even minor tears are bound to happen.” he indicated a previous rip in his sleeve, “I’ve sewn it and patch it up with sea silk from mollusks. I think you’ll find, gentlemen, that much of our resources come directly from the sea.”

“Will we be allowed to visit port at any time?” Sherlock quickly added, “Only, I will run out of supplies eventually and if I am to stay here I would like to record as much of my findings and experiments as possible.”

Watson seemed to genuinely appear sorry over his next words, “I’m afraid not, Mr. Holmes. While I’m sure your word of honour is true, I have been lenient before and it nearly cost me my life. I assure you I have plenty of ink and paper for your studies and we have quite the array of scientific equipment at your disposal. Do not despair yet gentlemen,” he finished with a gleam in his eyes, “The ocean is a wondrous place to behold! You will not regret your time here. I will take you to see marvels beyond your imagination.”

Sherlock’s heart stuttered at that. For a moment he was in his mind palace, looking at the dusty shelves and familiar clutter of 221B Baker Street, his flat in London… his home. It was not a gateway to the wonders of the world, but it had his memories embedded in the mantlepiece and in the piles of books for his studies and in the warmth of his plush chair that he would sink into after a long night and fade into sleep. In this space, a part of his brain creaked and groaned with the weight of realising he might never see his home again. And Mrs. Hudson would surely have to lease the place after he didn’t come back after a year or two. That place, that small shelter where time could stop and wait for him, would be gone, most of his rubbish thrown out or donated to some stuffy museum. Could he bear to know that he had given that up?

But then he looked at John Watson’s face and felt another part of his brain ease, and fidget with excitement. Here was some source of warmth too, perhaps not as familiar as the fireplace in 221B, but it was there, buried somewhere within the promise of a lifetime voyage, and the kind, glowing smile he was offering Sherlock at the moment. Watson nodded towards him and leaned a bit closer, “I believe you mentioned something about the engineering of my ship?”

Sherlock blinked several times before mumbling, “Um, yes, I’m not sure how this complex machine works. I’m afraid I had dismissed any rumours of underwater travel as fantasy.”

“Yes I… I noticed that.” he chuckled and tapped on Sherlock’s book, “In that case you’ll be needing your sketchbooks back, I believe?”

Sherlock nodded and Watson said a loud command from that odd language he spoke. If Sherlock was expecting Lestrade to enter he was surprised to find a member of the crew open the door and hold up his case, still preserved from the waterproofing, thank god. The crewman was a friendly-looking sort. After his temporary stutter over Watson, he gladly took the opportunity to deduce rapid-fire who the man was. Ship’s doctor, a bit nearsighted judging by his squint, but steady hands to sew up wounds when required, had been on board for nearly as long as Lestrade but with little medical training, mostly practical knowledge. Honest, open, maybe a bit too trusting, knew more than he let on. Possible ally should he need someone on his side.

“Mr. Holmes, Mr. Anderson, this is my good friend Dr. Stamford. He’s patched up quite a few of my men, even did a miracle on my shoulder. He’ll be taking you to your assigned rooms for the voyage.”

“Pity, I was beginning to enjoy the cell.” Anderson grumbled, but Stamford just laughed good heartedly and handed Anderson a bundle of clothes, patting him on the shoulder as he led him out the door.

The doctor, barely reaching Sherlock’s shoulders in height, looked up at him for a few moments and then smirked and handed him his case, “Good to have you here, sir. I hope you enjoy your stay.”

Ah yes. His indefinite stay, apparently. Sherlock frowned at that but attempted his best fake smile for the sake of appearances. It seemed to please Stamford because he then left without another word, not waiting for Sherlock.

“Is he.. should I?” Sherlock turned back around towards Watson, but the captain wasn’t listening. He was staring down at the picture of his sister and nephew, his mouth a thin line and his forehead pinched. Sherlock tried again, “Captain Watson, are you quite all right? Should I leave? I think the doctor left without me.”

The captain snapped back to attention, his posture immediately one of confidence and ease, “Oh yes, sorry about that, I told Stamford I would be dining with you before you went to your rooms. Would you like some breakfast, Mr. Holmes?”

Normally Sherlock would have said no. He sometimes went days without eating, much to chagrin of the estimable Mrs. Hudson. However, he had not eaten in quite a while and his hours in the cell and being battered about deck had made his body quite bothersome. As if on cue, his stomach grumbled and Sherlock, without thinking, squeezed his middle, wrapping his arms around him as if hugging himself would muffle his body’s demands.

Watson laughed at that and gestured towards the door, “That settles it then. After you.”

He lead him out of his office, down a brightly-lit hallway towards a bigger room. There were few doors at all in the submarine, Sherlock noticed, allowing sound from other parts of the ship to filter through the halls, and somehow Watson has managed to install wooden inner walls instead of steel to give a more comfortable resonance. Indeed, where he had expected metal and bolts he found rugs covering great stretches of the hallways and numerous paintings adorning the walls. His awe was not lost on Watson, who said nothing but watched his reactions like a painter stepping back to allow an art critic to value his work.

None of this, however, could have prepared Sherlock for the sight he would behold as he walked into the bigger room. When his jaw dropped in shock, Watson just chuckled and, for a brief moment, looked as if he was going to reach over and close Sherlock’s mouth, but he quickly aborted the movement and stepped into what must have been the dining room, gesturing around in pride.

Truly, Sherlock thought, this would be a marvellous voyage indeed.

**Notes for the Chapter:**

> Is it sad that I somehow managed to make this less gay than the original 20,000 Leagues Under the Sea? I mean… _“These words of the commander had a great effect upon me. I cannot deny it. My weak point was touched; and I forgot, for a moment, that the contemplation of these sublime subjects was not worth the loss of liberty.”_ Like… my god Verne calm down!
> 
> The _Casse-cou_ (thrill-seeker, daredevil) is pronounced something like [kehs-koo]. 
> 
> Most of this will vaguely follow some of the events in the original story, but with some obvious changes. Still not entirely convinced I’m imagining the gay subtext in the original though.  
> \---------------
> 
> Thank you for reading! Please leave a comment if you enjoyed this, I love hearing from you!  
> Or you could always follow me on [Tumblr](http://thebisonwitheadphones.tumblr.com/).


	2. Fillet of Turtle

Sherlock had only seen one dining room similarly furnished to the  _ Casse-cou _ ’s and at the time he had been a squirming, energetic child who cared very little what the lady with the crown wanted. Mummy and Father had gone on for weeks talking about these important people they would meet.  _ Once in a lifetime chance, my dear!  _ Mummy had said to him.  _ It’s to do with politics _ , Mycroft had explained carefully,  _ not that you would understand it. But when you’re in the very heart of the British Nation, adults tend to insist you wear your trousers _ .

_ Why? _ he had asked, scrunching up his face.

_ I don’t know, I’ll ask one, _ Mycroft replied. 

But Mycroft never asked, he just obeyed. If Sherlock had ever been under the illusion Mycroft was on his side, that occasion and many others had proved him wrong. The only other memories Sherlock had of Buckingham Palace were the blood red walls of the dining room and the scandalized shrieks when he waltzed into their boring party with only a bedsheet on. That had caused quite a ruckus.

The walls of the  _ Casse-cou _ ’s dining room were not blood red, but more of a warm auburn with amber and gold details carefully hand-painted on. It was also not nearly as long as the one at the palace, but the furnishing was so similarly exorbitant he could not help but wonder how much the construction of the submarine had cost. Probably half the British debt, maybe several times over judging by what looked very convincingly like a Vermeer painting. The ornate oak table in the middle of the room could seat 12 officers, and Watson pulled out a chair next to the head of the table, waiting for Sherlock to be seated before sitting down in his own spot.

Sherlock had been expecting a large spread of dishes on the table to try from, given the luxurious nature of the submarine so far, so when he looked down to see only a small, modest plate he felt oddly relieved he would not be forced to eat more than his small stomach could manage. His meal consisted of what looked like sausages and some form of pudding with… well, he’d like to say he knew what the last item was, but it was totally unidentifiable.

“I understand you are British, correct?” Watson tilted his head, “I have not eaten a traditional full breakfast for some years but my cooks and steward are masterful at their art and prepared this especially to your tastes. It is not quite what you’d find on land, but I can assure you everything is perfectly safe to eat.”

“And all of this is harvested from the ocean alone?” Sherlock asked, tasting some of the pudding and then nibbling a bit at the sausage. The taste was not unpleasant, though certainly strange. He continued to pick at his plate as Watson pointed out what each food was. The pudding was from red algae, the sausage from a herring (and here Watson paused to reassure Sherlock that his steward Angelo was the best of the lot). When Sherlock nodded towards the final part of the dish, Watson grinned.

“Ah, yes, that is fillet of turtle. I make sure every possible dish is served only by the sea. My men and I have been quite healthy for it.”

Sherlock stared down at the food, suddenly no longer hungry. He was not frightened by the identification of his meal, but all this talk of living only by the ways of the sea reminded him now of how he was to spend the rest of his life in this submarine. Everything exciting and new about the place would become boringly familiar over time. It was a beautiful vessel indeed, but a prison nonetheless.

“I believe I should like to retire to my rooms now, Captain.” Sherlock said, beginning to stand up.

“Call me Watson, please?” he stood up and put his hand on Sherlock’s arm as if to stop him, but then winced and sat back down again, his eyes focused on Sherlock’s barely-touched dish. “Perhaps you would be more agreeable to seeing the rest of the ship later? This afternoon?”

Sherlock bit his lip and frowned, wishing he could become invisible. Watson had been nothing but accommodating and conscientious during his time onboard. He nodded quickly and, before he left, grabbed one of the sausages to eat later. Watson chuckled at this and watched as Sherlock rushed down the hall, shouting directions as his guest left in an embarrassed rush.

\------------

It was difficult to track the passage of time in the submarine. Though the sound of waves brushing against the metal hull could be heard faintly at all times, there appeared to be no windows to look out from. Surrounded by the luxuries within the  _ Casse-cou _ , a scholarly mind could easily be enthralled for many weeks searching through book after book or gazing at each priceless painting so casually hung upon long stretches of wall, and yet never once know if the sun was rising or setting. To avoid impending boredom, Sherlock occupied his time by memorising in detail every single inch of his room. He was flipping through a book on cetacean anatomy when there was a knock at his door.

“Yes?” Sherlock called, but no one responded, so he stood up and opened the door to find a crew member waiting for him. This man did not seem to understand English, and when Sherlock asked for his name he simply shook his head. He pointed down the hall and led Sherlock up a flight of spiral stairs to a room where many officers stood bent over various complicated navigational tools. Watson stood at the center of the crowded room with a hand casually resting on the ship’s giant steering wheel, talking to Lestrade in a low voice. Lestrade said something that made Watson laugh, before giving him instructions that sent Lestrade to other parts of the ship. Watson then turned his attention to Sherlock, giving him a now-familiar grin.

“Impressive, is it not?” Watson came to stand by his guest, grabbing a pinch of Sherlock’s coat to lead him through the crowded mess of officers and crew, “I’m sure you’ve already been getting a good look at the controls.”

Sherlock nodded, even though he had not bothered to give a single glance towards the ship’s intricacies and had instead been watching Watson the entire time. He tried to make up for his peculiar lack of focus by paying more attention to the huge wheel Watson was showing him now.

“This is fascinating, certainly, but how do you see where you are going?” Sherlock indicated at the metal wall in front of the wheel. Watson’s smile grew even wider and he reached over to pull on a lever. 

Suddenly, in front of Sherlock, the round concave steel wall began to move, spinning out and away from the center revealing glass and beyond it a dazzling marine world that seemed to stretch on infinitely. If he only looked forward, he felt as if he was out there in the water, swimming amongst the schools of brightly coloured fish. A dolphin passed by the window and he stepped back, eyes wide. Watson laughed, a quiet, high-pitched giggle that caused Sherlock to turn and look at him with bewildered awe. 

_ Oh! _ His eyes… why hadn’t he noticed Watson’s eyes before? They seemed to be like a mirror held up to the sea -- dark in the submarine cell, but here, looking out at the open ocean with rays of sunlight streaming across the backs of fish, Watson’s eyes lit up with a pale turquoise. Did the man get everything from the sea, including the colour of his eyes?

“Do you like it?” Watson asked.

“Yes.” Sherlock answered without thinking, then frantically gesturing out towards the open ocean, “Eh-t-truly I have never seen such a… such a marvelous sight before. It’s quite… blue.”

“Well, I’m glad you feel that way. There are all sorts of wonders swimming about the depths, some of which I dare not let my thoughts linger upon for too long! Here we can live at peace. Here we are free from the laws and prejudices of civilization.”

Sherlock turned back towards the captain, “But is it truly worth it? You have family, am I correct? Do they know of your fantastic submarine?”

Watson’s expression closed off, and he crossed his arms, “They do not. I couldn't risk their lives. Anyone who would know of my creation would be subject to threatening or interrogation. They might not even know I am still alive.”

Sherlock did not respond and instead continued to gaze out through the window. The fish were gone but it was still a beautiful sight. “It’s as if I’m swimming out there. It’s a wonder you do not spend all your time here in front of the window!”

“Oh it is not the only one on this vessel; I have constructed several more throughout the ship.” Watson paused, his mouth quirking up to one side, “Would you… would you like to go for a walk?”

“Through the ship?”

“No, no, forgive me, I forget myself. Would you like to go walking out there?” He nodded towards the water, “I myself have a favorite location which I occasionally visit on hunting trips.”

Sherlock did not like the sound of hunting, but he supposed the ship needed provisions for its voyage. Besides, if he could be out there amongst the fish, he could gather far more accurate results for his notes on aquatic life. He nodded eagerly at the idea and Watson relaxed a bit.

“Right then. Shall we continue the rest of our tour?” 

The top floor of the submarine held the navigation room, the dining room, Watson’s and the rest of the officer's quarters, and at the very rear end the kitchen. The pantries held large stores of aquatic-sourced food, everything from various types of seaweed to a large, smoked swordfish. The steward Angelo readily boasted of the plentiful edible flora and fauna of the sea, but admitted to Sherlock is a low voice that he had some very terrestrial bottles of vintage wine he had snuck on board upon being hired on the docks of Italy. He then winked at Sherlock, saying something about possibly needing the wine for “later on”, but Sherlock just ignored the comment.

The lower deck contained both his and Anderson’s rooms. He found that there was only one spare bedroom, which had been given to him, while Anderson was to sleep in a hammock along with all the crew in their shared quarters. Instead of being offended by the gesture, Anderson had readily found other whalers and English-speaking sailors to play cards with, sharing stories amongst with the men. Perhaps it was for the best; Anderson felt comfortable among his own kind, while Sherlock felt comfortable in a room all to himself. 

Aside from crew quarters, there was also a very large library directly in the center of the submarine, filled with all sorts of wonders, taken both from land as well as the sea. Here they lingered the longest, Watson smiling whenever he saw Sherlock wandering off to look at bookshelves full of priceless knowledge. Sherlock spotted a jar that seemed to contain a strange sort of sea star with tentacles that still writhed about, clutching and clasping at the glass casing. He stumbled back in horror, but Watson patted him on the shoulder and ushered him onwards, offering no explanation for the creature. Sherlock had a feeling it had something to do with those ‘wonders of the sea’ Watson had mentioned. If this was what the sea contained, it was not surprising Watson kept its secrets guarded.

At the very back and deepest part of the  _ Casse-cou _ was the engine room, arguably the largest for good reason. Various giant machine parts whirled about, pistoning back and forth. Several men rushed around checking dials and adjusting bolts so the entire chaotic mess ran, to Sherlock’s amazement, with more precision and efficiency than any large land machine could have hoped to accomplish. Out from the steel-wired jungle came a somewhat shorter, sharp-eyed man who was dressed in a short-sleeved shirt and tough woven trousers, an oily rag slung across his shoulder. He wiped one hand and offered it to Sherlock, making eye contact for a bit longer than Sherlock felt comfortable with before turning back towards the captain.

“Everything’s in working order, sir. Is this your  _ guest _ we’ve been hearing about?” The man glanced back at Sherlock again, giving him a once-over with barely concealed disapproval. 

“Indeed he is. Mr. Sherlock Holmes, this is my Chief Engineer, Mr. Moriarty.”

The two men nodded at each other, but Moriarty's gaze was directed back towards the engine again, clearly not paying Sherlock any attention, “The diving hatch should be in working order, sir. Moran fixed it after that last incident.”

Sherlock quirked an eyebrow at Watson but he simply ignored him. Apparently, ‘the last incident’ was of little consequence to their current planned hunting trip. The captain thanked his engineer and led Sherlock back up towards the diving hatch, situated between the library and the engine room. 

Lestrade and a few of the crew were already there starting to suit up into some truly bizarre outfits, the helmets of which could only be described as very large copper-coloured bowls with bars over their portholes. Despite his suspicions, Lestrade assured him the suits had been tested well over a hundred times and were constantly checked to make sure they were in working order. A breathing tube was placed around his mouth and nose and was led out through a tight hole in a slick canvas full-body suit, up to a large oxygen tank to circulate a fixed amount of air. Sherlock could recognize the tank, at least, from the rebreathers coal miners had invented on land. 

But by far the most questionable piece of this whole outfit were the boots. Two thick, solid lead bars had been bolted to the bottom of the shoes, and when he tried to lift one it easily weighed about thirty pounds. 

“Those are to ensure you stay near the bottom. Makes it easier to walk around.” Lestrade explained.

“I was under the impression people who swam wanted to avoid sinking to the bottom. And how am I to get off the bottom of the sea when the expedition is finished?” Sherlock shot him a questioning glare.

Lestrade just shook his head and attached a tow line to his suit, tugging on it to make sure it stayed in place, before going over to one of the crew to help. When Sherlock looked over he saw to his surprise Anderson already fumbling about in his own suit.

“Anderson? You’re going along too?”

The whaler shrugged, “Of course. It’s not everyday you get to walk along the bottom of the sea. Besides, as I understand it we’re going hunting. Not that I expect whales here, but I’ve been hearing about large crabs in the area.”

Yes, of course Anderson would only be coming along for food. Sherlock, on the other hand, longed to bring his sketchbook with him on the journey, to capture the exact likeness of the different species of fish he would for the first time meet up close in their most natural state. 

Once all of the men had been suited up and checked to make sure their breathing tubes worked, Watson gave a signal and each of them plunged down into the cool depths of the ocean, slowly sinking to the sandy floor.

\------------

Mycroft Holmes had, of late, been forced to do quite a lot of legwork.

It was not something the Director of Military Intelligence usually said. All his missions and errands were placed in the hands of his capable assistant and employees, requiring of him only the occasional visit to India or France if conflicts were getting particularly nasty. However, over the past three years he had begun to notice a pattern of shipwrecks which, for a while, had not caught the public eye. Most had been attributed to being struck by a reef, or in more northerly regions icebergs. But it was Mycroft’s job to watch for any military advancements in technology, and based on the scant reports from informants in the Mediterranean, a new breed of warclass vessel had been designed, created, and now quietly roamed the open ocean. With so much political turmoil in the House of Commons, he had been forced to keep a wary eye out for news of this rumoured “submarine”, but not act upon it. After all, it was better to wait and see just what this new technology was capable of without letting its creators know they had been discovered.

Then both a British and French warship had been sunk in the span of a few weeks and newspapers had swarmed in asking questions. Some guesses were dangerously close to the truth, but most of the public naively believed it to be a sea monster or whale. Even his own younger brother had some fanciful ideas of a gigantic narwhal. He had allowed Sherlock his false hypothesis for as long as it had been convenient.

It had stopped being convenient when the  _ HMS Victoria _ barely made it back to shore, clearly scarred across the hull by the mysterious submarine. A list of persons alive and dead quickly confirmed to Mycroft one of his greatest fears: Sherlock was missing. No one had seen his brother fall overboard during the commotion, but it was obvious he had either fallen into the sea and drowned or had been captured by the submarine. With the security status of this new underwater ship reaching an all-time high, Mycroft had been given permission to use powers available to him to find and destroy whatever prowled the Atlantic Ocean.

Which was why the usually sedentary director was now storming down the hallway to the office of the Royal Navy Admiral, intent on getting whatever answers he required in any way possible.

Usually formal in his approach, he now entered the admiral’s office with no announcement, slamming a large set of papers down on his desk. Where he usually kept his face a neutral frown, he now glared down at the official with ill-hidden contempt. The admiral watched all of this with disinterest, his feet propped up on his desk and arms folded behind his head.

“Pleasure to see you again, Mr. Holmes. I take it you’ve come to discuss the use of my navy?” The admiral asked casually, as if offering Mycroft a cup of tea and not the use of an entire fleet of ships. 

Mycroft forced himself to calm down, straightening out his suit and sitting down in a chair that had not been offered to him. He sat rigidly in place, refusing a cigar and nodding again towards the papers, “Intelligence has been keeping their eye out for news of the submarine which, as you now know, stalks both domestic and international waters freely. There are over fifty accounts on record of sightings, everything from the odd fisherman to several enlisted officers.”

“A sea monster it then is not, I gather?”

“Most definitely not. Some of my informants first reported large sums of money being allocated to the steel industry about three and a half years ago. Over the following months, it appeared nothing of consequence was occurring, until this…” He flipped open a file, and a sketch on a torn piece of paper floated out onto the admiral’s desk. It was fairly detailed, showing the stark metal ribs of a half-built boat. It was unlike any ship within the Royal Navy, to be certain, but in the state it was drawn it could easily be ignored as simply an imaginative account of a foreign vessel halfway through completion. The admiral shrugged and gestured towards the rest of the file for more. Mycroft flipped to the written accounts of both the artist and other spies who had joined them. The descriptions were clear. This was no mere ship of a foreign navy. It was a private affair, created by a very wealthy individual who had done a diligent job of hiding as much of the construction of the submarine as possible.

“This sudden interest in finding the vessel… it would not by chance have anything to do with the disappearance of the late Mr. Sherlock Holmes?” the admiral smirked, leaning back into his previous position. 

“It is no secret that the relationship between my brother and I was… complicated at best. It was his own foolish decision to go traipsing off into the Atlantic, his fate is of little concern to me.” Mycroft said, though even to him his argument sounded a bit forced. But the admiral would need incentive to lend him some of his resources, and that wasn’t going to come from a personal rescue mission.

The admiral did not appear convinced, but nodded slowly, “I see. And this… submarine? It has been deemed a threat to the welfare of the British Nation?”

“Indeed, and France has become anxious as well, insisting we have something to do with the sinking of their warships. Now that it’s got out that we are searching not for an antagonistic sea monster but rather an advanced piece of technology, it would be best for both nations if this threat was located and, shall we say, taken care of quickly.”

The admiral nodded once and stood up to shake Mycroft’s hand, “Very well then, I shall lend a number of warships as I see fit to your intelligence agency, as well as the officers and crew to pilot them. Take care that your promise of efficiency is met, Mr. Holmes. I would not like to have such a villain haunting our waters for too long.”

With that, Mycroft found himself dismissed and with the armful of files he had dragged in, walking back down the halls towards the carriage that awaited him. The cool, slick sheen of the admiral’s hand and his sharp, piercing gaze reminded Mycroft of a shark honing in on its prey. The smile he had been granted upon making their deal had left him feeling a bit unbalanced as well. But he had gotten what he came for and now had, hopefully, a good number of ships under his command. Mycroft would now be able to set out to accomplish his true plan.

He was going to find Sherlock, and when he did, he hoped he would find him alive.

\------------

It seemed as if the hunting party walked along lonely, empty stretches of sand for ages, faint sunlight tracing lines across the plains. Their weighted boots kept them tethered to the sea floor, kicking up clouds of sand and tiny bits of algae. Watson plowed onwards at a demanding pace, barely glancing around, his helmet pointed straight ahead. Sherlock looked into the distance but saw only hazy nothingness. When he turned to Anderson, the whaler seemed just as bored as he, and the push and pull of the waves made their gait that of drunken men rather than intrepid explorers.

It was a true pity Sherlock could not communicate with any of his companions, for although he was used to keeping his observations to himself, he had of late felt a great desire to impress the captain with his deductions, despite his clear lack of knowledge compared to this man… this…  _ king of the sea _ ? No, that felt too much like Watson would wish to own this wild expanse. The captain was more like a traveler in a metal speck within the great blue. Yet even now as Watson walked towards an unseen destination, he seemed to neither float nor walk upon the ocean floor, instead observing as the ocean moved beneath him. When he turned abruptly and pointed towards a distinct dark rock wall ahead, Sherlock could not help but notice how Watson allowed his body to move in time with the waves. If he was not born of the sea, he had made himself an excellent denizen. 

Watson then motioned to Lestrade with a sweep of his hand. Lestrade nodded and, as they got closer to the rock wall, turned a knob on a large silver box he had brought with him. All of a sudden, a bright light lit up the murky waters. Sherlock saw now that they stood not in front of a rock walk, but rather a swaying mass of gigantic sea plants, jutting up from the ocean floor like mighty pillars. Lestrade stepped forward first, holding up his electric lantern so the beam shone where Watson was standing. The captain slowly reached his hand around one of the large fronds and pulled it to the side, creating a passage for them to step through. Lestrade held out the lantern and followed quickly behind as the two ventured into the forest and vanished from sight. Though Sherlock could not see Anderson’s face, he could tell from his body language that he was affronted by their sudden disappearance, but Sherlock charged headfirst through the wall of plants and into the dim world of the underwater forest. He could see Lestrade’s light a few meters ahead and followed behind them, until they came to where the plants were less dense and the sunlight began to shine through. Here, at a clearing, Lestrade switched off his light, and in its place the sun began to filter through onto the group of travelers. As Sherlock’s eyes adjusted, he could not help but gape. 

If Sherlock had thought years of anatomical studies and nautical dissertations could have prepared him for the world that now surrounded him, he was never more glad to be proven wrong. 

Large swarms of bright peach rockfish flew with the heaving sway of the ocean, some bigger than both of Sherlock’s hands put together. Clutching tight to the spindles of kelp were pale yellow seahorses, their curled tails latching around the shoots and bobbing against the brown and green streaked leaves. He couldn’t help but stare for several minutes, winding around in circles and stumbling through the underwater forest with wide eyes, trying not to blink in case he missed anything. Everywhere he turned there were more fish in dazzling colours, and quite a few times he almost stepped on an offended sea urchin. At one point, even Anderson had to grab him by the elbow so they could continue on, but as they climbed higher there were even more wonders to behold. 

As the hunting party spread out in search of food, Sherlock began to categorise every species of fish he recognised, wandering further into the forest. He turned a corner to find himself face to face with a sea lion. It startled at first, but then swam up close to him to rub its nose and whiskers against his canvas suit. He giggled and tentatively reached out to pet the seal, but it shrank back a bit and seemed to wait in place. When he stepped forward it backed up a few paces, and the cycle continued for several more steps. Sensing the game the seal was playing, Sherlock raced after the animal, and it tore off into the forest, easily dodging and diving and speeding far ahead of its new friend. When it saw Sherlock was struggling clumsily behind, it would turn back around and poke at his helmet, blowing bubbles in his face till he was forced to swat at it. The two continued for several minutes, Sherlock’s previous scientific endeavour abandoned for the antics of the sea lion. Eventually they chased each other back into a clearing where Watson was standing. Watson jumped back at the flurry of flippers, but doubled over in laughter when he saw Sherlock staggering behind.

Suddenly, the sea lion darted away into hiding, leaving the two humans out in the open, staring in confusion at its retreat. Then a hand signal from a nearby crewmate announced the arrival of what Sherlock feared the most in the sea: a great white shark.

The shark was quietly looming above the hunting party with obvious curiosity, but had not attacked, content to watch from its higher position. Watson reached out and lightly grabbed hold of Sherlock’s hand, seeing that he was beginning to shake uncontrollably. Watson then led Sherlock with the others as a group back the way they had come, forcing Sherlock to walk at a fast pace down towards the outskirts of the forest, all the while brushing his hand in a soothing gesture up and down Sherlock’s arm. When they finally walked through the wall of kelp out into the open again, Sherlock turned back to look, relaxing when he saw the shark had not followed them. Lestrade, however, who had been taking a head count, was beginning to look worried.

Anderson was nowhere to be found. 

Watson visibly sighed, holding up a hand to signal that everyone should stay put, charging back into the forest with Lestrade’s electric lamp in hand. Now that they had no light with them, they all waited quietly in the darkness. It was almost so dark Sherlock was afraid he had fallen asleep or been left in the middle of the open ocean alone. It was the same feeling he had experienced when exploring a cave as a young child and his candle went out, forcing him to sit in the dark for several hours before a rescue team found him, sobbing and wailing and chilled to the bone.

He reached out and grabbed one of the kelp fronds, swaying slightly in the current, straining to see anything. Then, somewhere out in the forest, a light began to frantically bob about, and he could hear thrashing and powerful arms and legs swimming and stumbling around. Without thinking, he rushed into the forest, flying through the tangled leaves till he reached a clearing. There, twisted up and caught in some long forgotten nets, Anderson was trying to pull himself free while also simultaneously keeping a watchful eye out for the now closer shark. The struggle had caught its attention and it began to loom closer. Near Anderson, Watson had set down his light to pull out a large knife, hacking away at the net. When he saw Sherlock he waved his hand to tell him to go back, but Sherlock joined his effort, tugging apart the nets.

Just then, something bumped against the back of Sherlock’s helmet and he shrieked, panicking and waving his arms about blindly as the shark swam right up against him, getting a very good look at his canvas suit. But its interest then turned towards Watson, who by now was caught up in the task of freeing Anderson, and before Sherlock could fully realise what was going on its mouth was wide open and it was charging towards his captain.

Sherlock was never quite certain what happened during those next few moments, but according to Anderson, the man had just gotten himself free of the netting when he turned around to see Watson being surrounded by a disturbing amount of shark teeth. The shark was attempting to get a bite of his suit, and Watson was only just now turning to see what was going on, so the heroic Anderson had no other choice but to tackle the shark head-on, lashing out with a mighty force against the great beast.

Lestrade, who had arrived onto the scene moments before, stated Anderson had simply bonked the shark on the nose and the poor creature had staggered away, swimming off to go find prey that would be a bit easier to catch. 

However it happened, when the party arrived back at the  _ Casse-cou _ and everyone had been properly removed from their suits, Watson made sure to extend a formal expression of gratitude to Anderson. 

“Thank you for saving me back there. It appears I am in your debt, sir.”

The whaler shrugged, “I’ll take your word on that, Captain.” He then mumbled as he walked back toward the crew quarters, “Not quite sure why I did it though.”

Despite Anderson’s careless response, he did indeed take Watson’s turn of phrase as a literal promise, intending full and well that he would one day take advantage of the captain’s gratitude. But for now he was content to get a good many hours of sleep in his bunk. 

Sherlock, however, did not find rest so easily. He lay in his bed for several hours, replaying the day’s events in his mind, searching all throughout his mind palace for a place to fit the details he now hoarded about the strange sea captain and his ventures beneath the sea.

**Notes for the Chapter:**

> Listen, Sherlock is a very tiny gay who’s experiencing his first crush and he just wants to play tag with sea lions and do science on the pretty fish. He can’t help it!  
> The creature in the glass jar Sherlock was scared of was a basket star. You’ve probably seen it in one of those Youtube videos titled “IS THIS A SEA MONSTER??!?!?!?” and it has like a bajillion arms. Yeah, those things.   
> Anyway, betcha can’t guess who the Admiral is, huh??? ~So mysterious~  
> \---------------
> 
> Thank you for reading! Please leave a comment if you enjoyed this, I love hearing from you!  
> Or you could always follow me on [Tumblr](thebisonwitheadphones.tumblr.com).


	3. White Coral

Everything was silent. When Sherlock opened his eyes, it took him a moment to recognise where he was. Above him the usually roiling ceiling of the ocean calmly swayed as the last hints of an evening sun trickled down and rested upon the sleeping coral reefs. A school of silvery fish wandered along the pink and golden expanse, parting to swirl around his body and rejoin again moments later. He looked down to see a crab scuttle across his feet, and he couldn’t help but smile when the tiny legs tickled him. He observed his bare, relaxed body, taking note of his pale skin, his smooth, large hands. It was as if the water did not even touch him. When he ran his fingers through his curly hair, a tiny, colourful fish darted out. He laughed.

And then he realised he probably shouldn’t be laughing under multiple meters of saltwater. 

His eyes widened and he choked, the sea suddenly surging forward into his lungs and blinding his field of vision with white bursts of pain. He struggled, launching himself off the sandy floor and trying to paddle up to the surface, but it was as if he was wearing the heavy boots from before. He sunk straight back down, squirming wildly and tossing about under the grip of impending death. As if to taunt him, the events of the aquatic world continued on as if nothing was happening. As if he wasn’t even there.

A hand landed on his shoulder, and lips brushed against his ear, startling Sherlock into momentarily forgetting he was in the process of drowning.

“Breathe.” a voice said, if it could be called a voice, registering more as a quiet, throaty command layered with the sound of the very plates of the ocean shifting against each other. Despite all basic instincts, Sherlock obeyed, taking in a deep breath, and to his surprise the ocean allowed him a fresh gulp of oxygen. Or… perhaps that was not correct, more like his lungs had changed somehow to allow for intake of saltwater. 

Bewildered, he swiveled around, searching for the source of the voice. He found himself inches away from the face of a creature so odd and otherworldly he could not help but startle. Two deep marine eyes stared back at him, and the fins on its neck fanned back and forth with the pull of the waves. Were he a poet, Sherlock would have immediately penned this creature a merman, but when he looked down, he saw not the fluke of a fabled siren but two legs from which grew long spindles of sea nettle. Pale blue and gold-tinged coral sprouted from the creature's arms and up the ridge of its back, and great swaths of seaweed curled around its torso. But perhaps most fascinating of all was the shock of white blonde hair that shot up from its head, glowing under the pale pink sunset. A twinge of familiarity gnawed at the back of Sherlock’s brain, and he recalled a faint memory of soft eyes and a kind smile. 

“It’s you.” he breathed.

The creature, perhaps partly John Watson and partly the sea itself, lit up at his recognition, and reached out with webbed fingers to tug at his bare arm, pulling him in close but not saying anything. So near those eyes, alien and human at the same time, Sherlock felt a strange ache in his chest, one that made him grin with delight.

Before he could realise what was happening, Watson was tugging him forward by the arm, and they began to swim. As they traveled further into the ocean, the last light of day extinguished and left them in a world of twilight hush. They seemed to glide faster than Sherlock could ever hope to swim, and a rush of exhilaration swept him further into the deep, till all was dark. Yet though he could not see Watson, he could feel his presence ever beside him, guiding him down. In the distance, he thought he could see a faint glimmer of pale green light. Soon they passed large square boulders and swam along what were surely ancient stone roads. Tall spires and giant walls grew up from the bedrock, a sunken city long forgotten to time, faintly glowing with undersea algae and deep sea fish. Sherlock’s heartbeat quickened. He reached out to grasp Watson’s hand, but they simply hurried along further, landing down within the walls of a temple that seemed to have been there since the formation of the earth itself. Sherlock could hear the distant calls of migrating whales, and the creak and groan of the stones surrounding them. It took him a few moments to realise the groans were not coming from the ruins but rather from his companion. When he glanced over at Watson, he saw not a trace of the captain in him, but rather an eerie creature, made half of man and half of sea. Perhaps in a previous life this had been a mighty explorer, but it was clear that the longer he’d remained married to the briny abyss, the more the two became one, a chimera of devotion and danger.

Another long groan came from this breathtaking creature, staring at Sherlock with hunger. Not the sort of hunger found in a predator seeking its prey, but rather something more base. It licked its bottom lip before surging forward, seaweed wrapping around Sherlock’s torso and bringing him closer towards the wild thing that had once been John Watson. Enveloped in the silky embrace, looking out at the ancient walls of a civilization long destroyed, Sherlock’s eyelids began to close as he allowed the sway of the current to rock him. It was only when he heard a low chuckle that he snapped his eyes open again, peering into eyes that were now completely black.

“Beautiful, yes?” the creature asked, and Sherlock could not tell if it was referring to itself or the city surrounding them. He took it to mean the latter.

“I have heard stories about such a place, but surely it cannot be true? How could such a place exist outside of legend?” he sputtered, “And why bring me here at all, why show me wonders I can never truly have?” 

He waited for Watson to answer, but the sea creature only grinned, showing flashing teeth, dragging him closer. 

Sherlock gasped when Watson -- no, the creature -- latched onto his mouth, pulling his lower lip down with its tongue before cradling his face in its webbed hands. He stuttered, but as the kiss deepened, he stilled, suddenly feeling as if the darkness around them held danger and he was only safe here, leaning into the creature’s touch. When it stepped away from him, Sherlock could see that some of the seaweed and coral had shrank back, revealing tender skin and a very human mouth, tilted up in a smirk.

When Sherlock truly awoke, tumbling to the cold, hard floor of the submarine, the remaining memory he had of the dream was standing there again in the sunlit lands, pink and purple dappling John Watson’s hair and bare skin. Not quite a captain yet, still young and pliant to the world’s ways, and eager. 

And if Sherlock had to reach down and finish himself off with startled, panicked breaths, moaning into the bed sheets that had fallen to the floor with him, he most certainly did not imagine Watson there with him, murmuring in his ear as Sherlock sobbed within the harsh, metal darkness of his new home.

\------------

When Sherlock opened the door to his room and stepped out into the hallway, he found that not only had his own room been dark, but the rest of the submarine was without light too. The familiar drone of the engines had silenced. Everything would have felt peaceful if he didn’t know what complete silence on a ship meant. He rushed towards the engine room, turning the corner to collide straight into Lestrade. 

“What’s going on?” he managed to ask, starting to breathe heavily. Lestrade almost ignored him, but noticed Sherlock stopping to bend over, panting hard. He rushed to Sherlock’s side, trying to steady him.

“Easy now, easy. It’s just a power outage, everything will be up and running soon. What’s ailing you?”

Sherlock patted his chest, squinting up at Lestrade’s face. Even the chief officer seemed to be having a harder time breathing, so he knew it wasn’t just him, but… he doubled over, feeling like his brain had been jostled free and was tumbling about inside his skull.

“Hey, sit down now, yeah?” Lestrade lowered him till he had his back against the wall, “Is it the air supply?”

He nodded frantically, clawing at the collar of his shirt, “Weak lungs, I’m afraid.”

“It’s all right, we’ll have the air filtering through again in a little bit. Sorry, it doesn’t usually take this long.” Lestrade patted him on the shoulder, “I forgot, you’re not used to being down here with stale air. Don’t worry, you’ll get used to it pretty quickly!”

Then the man was rushing off to the engine room again, leaving Sherlock with his knees drawn up to his chest, his head lying back against the woodgrain.  He ran his long fingers across the thick rug underneath him, trying to ground himself in the texture of the carpet. He heard several more men running about, and his vision began to clear just as one of the crew knelt down to check on him, asking him something in French. He was too light-headed to translate anything and simply shook his head with a lack of comprehension. The sailor left and then returned with the familiar, friendly face of Mike Stamford, who must have been told of Sherlock’s troubles already, as he came with his doctor’s bag.

“You feelin’ a bit poorly, Mr. Holmes?” Stamford chatted to him, checking for fever and other various signs of illness. Sherlock explained his weak lungs to the doctor, all the while trying to listen for any more sounds of what was going on in the engine room down the hall.

Stamford was just about to give him the same assurances Lestrade had said earlier, when Watson thundered down the hallway, roaring above the ruckus of crew crowding near the engine.

“CLEAR OUT! EVERYBODY CLEAR OUT! WHAT’S GOING ON HERE?” 

Many of the crew backed out down the hallway to give him some room, and once he had everyone’s attention he shouted towards the chief engineer, “Moriarty!”

The man in question stumbled out from under a large machine part, wiping his hands on a rag, “Just an unexpected bit of engine trouble, sir, nothing to worry about. There will be fresh air and restored power in about five to ten minutes. I’ve got all my men working on it right now.”

Watson nodded shortly and turned back towards the rest of his crew, “Go on then, you heard him. No need for the commotion, get back to your posts.”

The men obeyed, a few grumbling under their breath about lost sleep and a few talking in that strange language Sherlock had heard intermittently throughout the voyage. He got up from where he was sitting, expecting Watson to fuss over him worriedly. Instead the captain saw him and immediately stiffened, standing straight up with his brow furrowed. He stormed over to Sherlock and Stamford, gritting his teeth.

“Doctor, would you kindly take our guest back to his room?” Watson said, and there was no possibility of suggestion in his voice. The doctor grabbed Sherlock by the elbow without question, leading him back.

“Wait wha-” Sherlock turned back towards Watson, “What’s going on?”

“I’m sorry, Mr. Holmes, but I fear you must stay in your rooms till morning. We are about to head into rough waters and I can’t have guests out wandering around taking up space in the hallways. My men will have to work this much harder now that we are running late with the engines down. Stay in your room and ask no further questions.” The captain answered briskly, and was rushing up towards the front of the submarine without further word. Something in Sherlock felt very, very wrong, and he wanted to warn Watson, but was helpless as the good doctor did as he had been instructed. Stamford nodded his sympathy, and Sherlock was expecting the man to leave him, but instead the man joined him in his room and shut the door behind him, setting his bag down with a heavy clunk.

“You’re… you’re staying with me?” He frowned.

Stamford smiled, pulling a well-worn book from his bag and placing it down on a small table next to two chairs. They both sat down and he leafed through its pages, some of them wet with spots where the ink had run.

“This is one of the few things, aside from my medical equipment, that I kept with me from my life on land.” he said, propping the book open to a sketch of a dissected heart, “I didn’t get any proper medical training, but I managed some apprentice work for a few years and snuck into the university libraries while everyone thought I worked there.” He huffed with a hint of a mischievous grin, flipping to another page.

“Why are you telling me all this?” Sherlock curled up in his chair and wrapped himself in one of his blankets, preparing for a long night.

“I’m tellin’ you because you can’t forget.” Stamford said, “I don’t mean to speak ill of the captain. This is by far the greatest marvel of mankind I’ve ever seen, but…” he lowered his voice, wringing his hands, “Do you have family, Mr. Holmes?”

“No.” he answered, then thought about it, “...yes. Yes, I suppose I do. Though he’s a rubbish big brother, and there’s nobody else. No one who’d care if I’m gone, except maybe my landlady.”

Stamford sighed, “Then you’ve already forgotten.”

“I’m not! I don’t!” Sherlock sat up in his chair, frustrated at how very lacking the conversation felt. What did the doctor want?

Even more frustrating, the doctor did not say much after that, instead flipping through more of the pages, till Sherlock scooted his chair across to lean over his shoulder. They both read through Stamford’s notes, using their combined knowledge to pick apart the wrong details or measurements, which made Sherlock remember his own book sitting in Watson’s office. How could he combine the usually cheerful version of the captain with the one he had seen tonight, practically livid at everyone for merely existing?

“Did he forget?” he asked, cursing himself inwardly as the doctor would have no idea what he was referring to. But Stamford, magically, seemed to understand him perfectly.

“Yes.” he adjusted his glasses, “Yes he did. Which is why I mentioned it to you. He loves the sea, and I think sometimes he tries to escape humanity by getting himself into more trouble.”

“What do you mean?” Sherlock asked.

Just then, the ship careened, lurching onto one side, and both men tumbled to the floor, trying to grab hold of something. Outside they could hear loud thuds, probably some of the books in the library falling off shelves. The submarine veered to the other side and then righted itself, but only for a moment, before it began to bob up and down again.

“What in heaven’s name?” Sherlock cursed, trying to stand up. He looked to Stamford for an explanation but the doctor seemed just as surprised as he. From somewhere up above he heard a very loud crash and a scream, and the  _ Casse-cou  _ continued to toss in the current, sending all sorts of things flying loose. Sherlock gave up trying to stand, joining Stamford in his hiding spot under the bed. He gripped the metal frame, reminded very much of that first night on the deck of the  _ Victoria _ , at the mercy of the wind and waves.

When the submarine finally righted itself and everything was balanced again, the power and lights came back on. The engine roared to life with the same steady beat, as if had never stopped, but over that noise there was the unmistakable cry of a human shrieking in horror. Sherlock could bear it no longer, bursting out into the hallway with Stamford following quickly behind, clutching his medical bag to his chest. 

What they found, once they got past piles of broken objects and up the flight of spiral steps, was one of the crew members lying on the floor with his skull cracked open against the steering wheel. There was an obvious cylindrical hole puncturing his head where one of the pegs must have entered. And kneeling above him, with terror splayed across his face, was John Watson, cradling the dead man’s head in his hands, his entire body sobbing. Some of the other crew had also arrived, all staring at the bloodied mess. Terrified to look but unable to stop.

Lestrade was the one to finally take control of the situation. 

“Step back a bit, let me through please.” The man said in a firm voice, pushing his way to the center, insisting those behind him go back to their quarters and continue as they had before. He then quietly grabbed a towel from one of the engineers and wrapped the dead man’s head, trying to soak up as much blood as possible, while Stamford got behind Watson and pulled him away from the corpse. 

“Holmes, help me will you?” Lestrade nodded towards the man’s feet. Sherlock bit his lip, but helped carry the body towards the other side of the room where a few of the crew had already laid out large swaths of cloth. When they returned to where Watson sat, Sherlock couldn’t help but pull him into a one-armed hug, trying to get the man to calm down. Already now Watson was beginning to come back to reality, looking around at the blood-stained floor with broken helplessness.

“Beggin’ your pardon, captain, but we need to know what happened. Did you see him die?” Stamford asked quietly.

Watson shook his head slightly, “I… no, I never saw him get struck, but he was still alive when I found him. He…” his breath came out as a sob, “I tried… I tried to put it all back in, but it was too late…” He did not say anymore, curling up into Sherlock’s and Stamford’s arms. Not a single man in the room blamed him.

Sherlock had been right. It was going to be a very long night.

\------------

As soon as the storm passed and the sea was calm again, all essential crew stayed on board, as did Sherlock and Anderson, but the rest donned diving suits and breathing tubes in communal silence. Sherlock watched their movements, ritual and careful. Whatever was about to happen, it was necessary, but also grimly ceremonial. When the body of the crewman was brought up to the top hatch to be let out that way by four men, it became obvious what was about to happen. Watching from one of the submarine’s bigger windows, Sherlock and Anderson saw Watson lead a group of six officers and six crew members to the shallow bottom below. 

From up above at the surface, a few men without lead boots grabbed hold of a very tightly-wrapped and weighted funeral casket, carefully dragging it down to the bottom where they handed it off to four of the officers. Though he could not tell who was in which suit, Sherlock knew one of the bearers was Lestrade, and the man at the head of the group was Watson, leading them down to a bed of coral reefs. Where Sherlock had expected to see bright bursts of colour, the coral instead was a very odd white, and brittle. It gave the whole section of reef the appearance of a pale pile of bones, and at the edge of the hill some of the men had already dug an elongated hole where they would bury the body. 

When the procession stopped and formed a semicircle around the hole, Watson held out both hands, in a ceremony Sherlock had never seen before. Those who did not hold the casket also held out their hands till they were joined, all reaching out over their comrade. If Sherlock had to guess, the men from the crew were those who were either related to the deceased or were good friends of his. 

One of the men faltered, collapsing to his knees and sinking in amongst the bleached coral and wafts of stray sand, but nobody scolded him or motioned for him to get up. One of them who stood beside him even knelt down with him, attempting an awkward hug in the large canvas suits, their metal helmets resting together. The rest of the procession carried on in silence, laying the body down in its final resting place and filling up the grave with silt, covering the small mound with nearby coral. Only then did Sherlock notice a few other mounds next to the new one. This wasn’t a random spot they had chosen; it was a burial ground. Their burial ground, where their loved ones and friends lay.

The man who had fallen to his knees had to be held up by two of his friends all the way back, and when they finally surfaced in the submarine again, Sherlock could sees tears streaking down his cheeks, mumbling something and rubbing at where a thin silver band rested on one of his fingers. 

While most of the officers and crew went back to their original stations, Watson joined Sherlock in the library to stare out at the reef below. He then stepped back and cleared his throat.

“Um… Sherlock, could you…?”

Sherlock turned around to face him, and he could see Watson fidgeting, scratching at the back of his neck, and looking anywhere but at him.

“Yes?” he prompted, stepping closer towards Watson, desperately wanting to reach out and smooth his hand down the man’s arm as Watson had done for him in the kelp forest.

Watson cleared his throat again, “I’ve thought it over. Quite a lot actually. Em… you see,” he straightened up a bit, finally making eye contact. “You’re no longer a prisoner of the  _ Casse-cou _ . You’re free to go. Anywhere you like, anytime you like. If you want to leave, I will not blame you. I trust your word enough that you would keep my men’s lives and my own existence as much of a secret as possible.The same is true for Anderson.”

“You are not afraid he or I will go and tell others about this submarine?” 

Watson shook his head quickly, “No, no of course not. Not anymore. Anderson… is a risk, I confess but…” He took a deep breath and then, as if that had settled matters, he began to walk quickly down the hall.

“But why? What changed?” Sherlock followed after him, knowing he shouldn’t press things but desperate to understand.

Watson’s answering laugh was terse and bitter and cut short by a sob. He closed his eyes again and shook his head, fists clenching. Deep breath. Repeat. 

He could not look at Sherlock when he finally answered, “Because you are the most beautiful man I have ever met. And I can’t lose you.”

**Notes for the Chapter:**

> I promise the next chapter will be happier, I promise!   
> The crew member who died wasn’t anybody in particular. But yes, just to be clear, the guy who was crying at his funeral was the dead man’s husband. Sorry.  
> \---------------
> 
> Thank you for reading! Please leave a comment if you enjoyed this, I love hearing from you!  
> Or you could always follow me on [Tumblr](thebisonwitheadphones.tumblr.com).


	4. I Dreamed of Atlantis

John did not see himself as a very complicated man. When he looked at the advanced piece of machinery he lived in, he saw not the brilliance of his own design but the hard, dedicated work of his crew. Their devotion was built into the woodwork and metal gears, the ever-churning engine, and the handpainted details of the dining room walls. Without his crew, none of this would have been possible. Four years ago, sitting in front of piles of books and reams of paper, he had thought his ambitions too lofty and nearly impossible. If he had dared breathe a word of an underwater metal ship that swam freely through the ocean, he would have feared charges of insanity. Only one other man had seen his intricately detailed plans, and even he had at first scoffed at the outlandish idea, cautioning John against trying to build such a dangerous contraption. James Sholto had meant well, and his words were wise, so John had put away his ideas, dismissing them for the time being.

Only when he and James had been caught together in bed did dreams of living a world away from the cruel laws of man seem desirable again. But time had been against him, forcing John to flee with as many of his blueprints as he could gather on the very night his lover was dragged away to court. 

But those were old memories. Old, very bitter ones. So John sank himself beneath the waves in his little submarine, taking with him the faithful builders of the  _ Casse-cou _ and accepting several other men from various ports across the world during their travels. This crew, this rather awkward bunch, with their own invented language and code of law, were all wanted men of the law. But here they were all safe. 

At least, that was what he had told himself.

He did not say anything to Sherlock after his rather blunt confession that terrible night. Instead, he stormed back towards his own quarters, hoping Sherlock would leave well enough alone and simply accept his words as mistaken. Perhaps if he simply assumed John was emotional from the death of one of his men, he would ask no more questions. John was lucky enough to find himself alone when he reached the door to his room, so he plunged himself into the suffocating blankets. Some part of him wished he would actually die this way, eventually running out of oxygen and slipping peacefully into nonexistence, but no. Instead he awoke the next morning with a throbbing headache, sprawled on his back and staring up at the creaking ceiling. He slowly rose to a sitting position, muscles aching and eyes raw from tears. It wasn’t the first time he had started the day in this condition, but John Watson was nothing if not determined, so he got up and went to check on his crew.

It was a surprise to see that when he entered the dining room to eat breakfast he was not alone. Sherlock was already at the table, his fork twirling a bit of seaweed around in circles and his eyes staring off into the distance. John tried to exit without disturbing him, but Sherlock jolted back to reality, almost tripping over himself as he rushed to stand.

“Watson are you quite alright? Did you get any sleep?”

John offered what he hoped was a reassuring smile and sat down at the head of the table, leaning back to let Angelo serve a plate of steaming food. When the steward left, he motioned for Sherlock to join him, but Sherlock’s plate remained untouched.

“I am quite well-rested, thank you. Yourself?”

No response. He looked up from his food to see Sherlock staring at him with very large, sorrowful eyes. John’s chest began to ache, and he winced, ducked his head down. It had been far simpler to ignore his emotions when he had first seen the man, beautiful but unreachable, in his own world of extraordinary deductions. Now the piercing eyes has become softer, more worried. When he felt a hesitant hand on his own, he jerked away, almost falling out of his seat. Sherlock hesitated, then resumed holding John’s hand, giving it a light squeeze.

John coughed, not knowing quite what to do, “I’m afraid there must be a misunderstanding, I...”

“Did you mean it?”

“What?”

Sherlock rolled his eyes and repeated himself slowly, “Did you mean it? Last night, when you said… you said I was…”

John felt his left hand beginning to tremor slightly, and he quickly slipped it under the table, trying desperately to latch onto whatever Sherlock was telling him.

_ The most beautiful man I ever met. _

Why had he said that? It was true, probably truer than a lot of things he had said of late, but he’d been content to hide his desires, knowing full and well Sherlock was not like the rest of his men. He had no certainty of Sherlock’s attraction. The ache in his heart was growing stronger, and in a desperate attempt to cut off the first sounds of a sob, he straightened up again and cleared his throat.

“Listen Sherlock, whatever happened last night, it was purely a nervous reaction. Nothing more.” If he had hoped the lie would make him feel better, it didn’t, instead settling in like a heavy weight upon his shoulders.

“ _ ‘Sherlock.’ _ ”

John squinted, “What?”

“You called me Sherlock. Last night and against just now. Did you mean it?” Sherlock was now leaning in very close, his finger curling around John’s wrist. He held them still for a moment before a small smirk appeared on his face.

John stuttered, “No, no, it’s... that wasn’t…”

“Quickened pulse. Widened pupils. All the signs are there.”

John did not have to ask for clarification. His heart thumped against his chest. He waited for the laughter or the sneers, for the man to get up and storm off in an insulted rage, but found Sherlock starting to smile, now mere inches from John’s face.

“Did you mean it?” Sherlock asked a final time.

“Oh god yes.”

And that. That felt good. The words felt like months of exhaustion being lifted right off his shoulders. It felt like a cool misty rain rolling in and bringing him relief. The admission seemed to have a similar effect on Sherlock, who gasped, tilting his head down to hide reddening cheeks. 

John couldn’t help himself, reaching up to cup Sherlock’s face and kiss him. It was a very light, chaste kiss, but could as well have been an electric shock. The two ended up with their foreheads pressed together, Sherlock’s curls getting in John’s eyes, but he didn’t care. Breakfast was forgotten as the two tried to stand up in unison, instead tumbling into a tangled sprawl on the floor, their initial giggles turning into fits of laughter. 

After quieting down, John stood, helping Sherlock up, not letting their hands go. Only when Angelo returned did John remember where they were.

“Sherlock, could… would you like to perhaps meet me again this evening? In the library?”

Sherlock nodded eagerly, and tugged on John’s hand when he turned to leave, “Watson?”

“Just call me John, yeah? Seems a bit more appropriate.”

So for the rest of the week, Sherlock took every opportunity to call John by his first name. And when Lestrade and some of the other officers started giving John knowing winks, he just swatted at them with a wide grin, ordering them to get back to work.

\------------

Sometimes, when the night was growing long and the sea was calm and there was nothing but a blank darkness outside the round windows, a quiet night was called. They would plant the  _ Casse-cou _ on the ocean floor, or on an underwater hill where it would not drift, and the crew would shut off the engines. Everyone would be given the night to rest or read or talk. It had been a while since they had gotten such an opportunity, between the temperamental nature of the Atlantic and their captain’s insistence that they stop by every notable natural or manmade feature that the ocean could possibly hold (or so Anderson claimed, despite his own curiosity). However, as they neared their next destination and located the seamount which they were aiming to settle on, John ordered a quiet night to be called. 

Usually John enjoyed quiet night. He took the time to go down to the crew’s quarters and plays games and share stories with his men, occasionally rousing one or two of them to get out their instruments so they could all sing. This time, however, there would be no time for talking or singing. He turned down the lights in the library, leaving only a few lamps on, and then sat down and waited as a messenger went to find Sherlock.

John had never been so anxious in his life.

The submarine was just settling to a stop on the ridge when Sherlock entered the room, startled a bit a the lack of light but otherwise eagerly coming over to join John where he stood gazing unseeingly out the window. Outside there was nothing but pitch black, they were so deep, and when he turned to look up at the stark outline of Sherlock’s face, he saw concern and uncertainty. 

“John? Is something wrong?” he asked in a low voice.

John smiled kindly up at Sherlock and carefully wrapped an arm around his waist, drawing him into a hug. They stood there together for several moments, simply listening to the quiet roll of the passing current.

“Um, John? Are you…?”

“I’m fine, I’m fine.” John finally looked back up. In the dark room, Sherlock could see John’s eyes were a deep indigo, and filled with apprehension, almost fear. Before Sherlock could ask him again, John squeezed his hand, “I’d like to ask… I’d like to know if you wanted to go out with the men tonight for an expedition?”

“That isn’t at all what you’re asking, you wouldn’t be looking at me like that if it were so.” Sherlock replied firmly. 

John’s face broke into a grin, and he nodded his head, “Right, sorry I’m not so good at this sort of thing.” he paused, then tried again, “Have you heard of the  _ Consolid _ _ é _ ?”

“Vaguely, mostly from old sailors when I was a child.”

“Yes?”

Sherlock shrugged, gazing out at the inky black, “Any man who has sailed the sea for some time is allowed his share of fantasies. I assumed the  _ Consolid _ _ é  _ was one of them. French warship that turned traitorous and attacked British and French alike, gathering treasure as it went. Then it robbed a ship full of cursed gold, and the curse went with them. Eventually the captain and his crew went mad and they were dragged down to a watery death during a freak storm.” he smirked, glancing down at John, “I suppose you’re going to tell me that the ship is real, you found it, and that’s where we’re going?”

John bit his lip, “Well, yes and no. I did find the ship, and as you guessed the tale has roots in truth. No body died in the sinking, though, they all abandoned ship before that point. Never heard of any curse, that must have been added later by those sailors you mentioned.”

“Giving me a history lesson, are you?”

“Now, now, don’t be like, there’s a reason we came specifically to this place. The  _ Consolid _ _ é  _ didn’t have any curse onboard, but the captain did find treasure, and picked up quite a lot of it.”

Sherlock sighed, dragging John back into a hug, “Anderson is the one you should be talking to, not me. Surely by now you know me well enough that I don’t care for gold.”

“Would you care if I asked you to find two rings?”

There was no response. John turned to see if Sherlock had heard him, but the man was standing completely still, his eyes blinking rapidly. When John asked the question again, Sherlock just bowed his head and closed his eyes. Then, suddenly, they snapped open again and the familiar piercing gaze returned.

“Are you asking… you would actually want me? You would… forever? I mean, for the rest of our lives?”

“I’d certainly hope so.” John pursed his lips, “Would you like that? Here onboard, with the men, any marriage is considered acceptable, no one would be able to say otherwise.”

“Is that why you left? Is that why all of these men are here?”

“Yes.” John answered quietly. He carefully took hold of Sherlock’s hands, bringing them together into a warm grip. 

Sherlock nodded slowly at first, then rapidly, his lopsided grin growing wider by the second, and John pulled him down for a long kiss. They stood there for several more minutes, forgetting all about the darkness outside or the rest of the ship. For that time at least, they were the only two in the world, their tears lighting up their eyes like sparkling stars in the night.

\------------

John was nervous. He knew that Lestrade would keep a careful eye on Sherlock as they explored the sunken wreck, and would ensure that all of the team returned in time. Despite this, ever since Sherlock had suited up with the others and plunged into the deep, John had sat at the large library window, peering out of the circular glass with increasing impatience. Hoping, struggling to see any signs of their return. 

He must have dozed off at some point, for suddenly he awoke to the sounds of the team returning, sloshing around as they removed their suits and wandering towards their quarters, chatting to each other in that rather crude blend of Sabir and Polari he had invented as the official language onboard. When he had first gathered all of his crew, the rather awkward bunch of seamen from all over Europe had been unable to fully communicate with each other. This had left him with the option of creating a combination of the language of the Mediterranean and the covert slang he had known so well from his past life in London. To see those traces blended amongst the safe and happy men onboard his ship eased John into a sense of comfort. Everything was fine, everything was good.

Some of that nervousness fluttered to life again when he saw Sherlock rush in. The man sped past the library as quickly as he could, not looking at John as he went. He clutched his large hand in a tight fist against his chest, a faint smile on his face which he was desperately trying to hide. 

Before John could ask what he had found, Sherlock ran off to his quarters, and he could hear the door shut, though it didn’t slam as much as close very quickly, as if to ensure the secrecy of the find. John sighed and went off to go check on his men, knowing that he would otherwise spend the rest of the afternoon worrying over Sherlock’s actions. That would not do at all, so he instead spent the rest of the hour in the lower quarters, his crew sending each other knowing glances behind his back. And Sherlock spent that time carefully cleaning his treasure, sending messages to the staff and steward. All would be perfect, he hoped, by the evening meal.  _ Everything must go according to plan, _ Sherlock thought, polishing his chosen items,  _ Everything must be perfect.  _

As the midnight hour fell upon the hushed submarine and its inhabitants, a bottle of Angelo’s vintage wine and two plates of the finest non-seaweed dinner the cooks had to offer were placed on the small table in the captain’s quarters (along with, Angelo insisted, appropriate mood lighting in the form of a tall wax candle). This was the sight that greeted John when he entered his quarters, huffing in laughter when Sherlock eagerly pulled out a chair for him. The meal, as it turned out, was peacefully uneventful, the two exchanging familiar conversation as they would have done in the far grander dining room. But even as they finished and the plates were taken away, the door swinging shut and bringing with it a sense of privacy, Sherlock feet tapped nervously on the floor and his knuckles gripped white.

Finally, he stood up, reached into his pocket, and drew out two small rings that were dwarfed by the size of his hand. John led Sherlock over to sit on the edge of his bed, one hand rubbing circles into the small of Sherlock’s back as the other reached and picked up the first ring, holding it up to get a better look.

The first ring was actually a silver spiral, tightly wound. Both ends tapered into two curled hands, which when clasped together formed a solid bond. Hidden in between the connected hands was a tiny heart, invisible to anyone else but the wearer. John tested it on his own finger and found it was a bit too big for him, so he reached for the other.

The second ring was a fairly plain gold band which contained a small pearl embedded in it. Wrapped around the pearl was a miniscule engraving of swirling waves, evoking images of surging tides and white capped fringes. Inscribed on the inside there were the words  _ medhel an gwyns _ .

When he tried this one on it fit almost perfectly, and from the excited look on Sherlock’s face this was the one he had picked out for John.

“The inscription? D’you know what it means?”

“No idea.”

John smirked, “So either it’s something beautifully romantic or dreadfully boring?”

“Hopefully the former, but if not we could always pretend.” 

John just laughed and went to put on his ring, but Sherlock stopped him, shyly taking the ring from him and then waiting. John obliged and held out his hand, letting Sherlock slip the pearl and gold band onto his finger. He then did the same for Sherlock, the two silver hands clasping tightly together. While Sherlock gazed down at his new ring, John moved closer, nudging till he could properly kiss him. As he deepened the kiss, he began to push Sherlock down onto the bed, at first eliciting giggles from his lover until it became obvious what John was wanting to do. Then Sherlock sat bolt upright and scooted further up the bed till his back was resting against the headboard, his body curling up into a tiny ball. John stayed exactly where he was, not wanting to spook him.

For a while everything was quiet. Sherlock traced patterns into the sheets, his knees drawn up to his chest. John said nothing, watching him carefully, an understanding smile just barely visible in the candlelight.

“Can I tell you something?” Sherlock asked quietly.

John crawled up next to him at the headboard, slowly wrapping his arm around Sherlock’s shoulder. He leaned in close, letting his lips brush against Sherlock’s ear, “Anything you want, love.”

Slowly, Sherlock raised his head to look out at the dark room, and took a deep breath. 

“I dreamed of Atlantis. A few nights ago, you were there, you were some sort of… otherworldly being, who took me to a city that does not exist in myths that should not be true.” he gasped as his body shuddered, his vision getting blurry, “We came to this temple, there was sunlight shining down on the coral… the stones… your golden hair… a-and… I remember, I asked you why you had taken me there. That it was impossible. But you didn’t answer, you just… kissed me. And I liked it.”

John was silent for a few moments, and then he moved to sit directly in front of Sherlock, carefully taking Sherlock’s trembling hands in his own steady ones. “I think I did answer you, in a way. When I first saw you, and you were jumping around making deductions, and your eyes lit up... I wanted to show you the impossible. That’s what we are, this vessel, these men… me. We shouldn’t exist, our shelter, our happy ending. But it does, just a little bit.” he smoothed his hand down Sherlock’s arm, drawing him into a hug, “You are safe here. I’ll always make sure you’re safe. I want you to know how much you matter.”

“Romantic.” Sherlock scoffed, even though his words came out a bit choked. He grinned, and John giggled a bit too, though neither would ever admit it later.

When they started to move again, John carefully unbuttoned their waistcoats and shirts, running his hands along the side of Sherlock’s legs as he took off his trousers, until they both sat in only their pants. John slipped out of his, but let Sherlock remove his own, at first edging them off carefully before becoming impatient and dragging them off altogether, revealing his stark pale body in the warm candlelight. John settle down next to him, running soothing circles across his now bare body, and as he did all of the racing thoughts in Sherlock’s brain began to slow to a blissful quiet.

They rolled back onto the bed, sliding against each other till John was settled on top, his arms wrapping Sherlock in a grounding embrace. He then leaned in close and nuzzled his chin into the crook of Sherlock’s neck, placing soft kisses along his skin, making his way up to Sherlock’s ear. He nipped at it a little, enough to make Sherlock shiver, in a way that made his heart beat faster and blood flow downwards. 

“Good?” John murmured.

Sherlock nodded, and John cupped his face, using his thumb to pull down Sherlock’s lower lip and tilting to plant a kiss on his cupid’s bow. The moan that resonated from Sherlock left John breathless, looking down at this precious man spread out beneath him. When John’s beard brushed against Sherlock’s jaw, Sherlock’s head fell back with a gasp, before he pushed himself up to rub against the coarse hair.

“Mm, you like that?” John grinned and made his way down to Sherlock’s chest, thumbs brushing over his sensitive nipples, down his sides, his back, until John was nestled between Sherlock’s legs, running his beard against Sherlock’s thighs while his lover bit back several moans and panting gasps.

“John I… I,” Sherlock shuddered and reached up, settling his fingers in John’s hair and pulling him close, their mouths clashing together uncoordinated, smoothing into a deeper, firmer kiss. Their bodies rubbed together, hands sliding, kneading, grasping. Sherlock felt John cupping his arse and pulling his hips up towards his own, and Sherlock splayed his legs wide, unsure quite what to do but desperately, definitely needing to. John instead scooped up his legs so that they were resting on his shoulders. He then bent over, letting his eyelashes flutter against Sherlock’s quivering stomach.

“Tell me what you want, love. Anything, whatever you like, whatever you’re comfortable with.”

“I… can you…” Sherlock’s cock brushed up against John’s and he gasped, his body arching and his head falling back onto the pillow, “Fuck, just just please, I need you  _ please. _ ”

John braced his weight with one hand against the headboard and used the other to spread Sherlock’s legs further. He leaned down to slip a finger into Sherlock’s mouth, his eyes flittering shut as he drew his finger out and moved down to brush it against Sherlock’s entrance, softly whispering  _ relax, it’s okay, you’re safe _ , before sliding the first finger in, taking his time to prepare him. Sherlock’s cock ached, and he squirmed to try and push John in deeper. 

“John.” he gasped between breaths, his eyes squeezed shut and his fingers gripping John’s thighs, trying to get him to move closer. John slid a second finger in while brushing his coarse beard along the inside of Sherlock’s thighs, causing Sherlock to whimper, before drawing back out to grab a small bottle of lube.

“For god’s sake, John, please--” but then John scooped his legs up again and slowly slid into Sherlock, and for a moment all coherent thought grounded to halt. He felt… good, whole, complete. His throbbing, leaking cock made him gasp, breathing hard and biting his lip when John hit right there  _ right there _ just where he needed him to. When he started to groan, John took Sherlock’s cock in hand and started to rub quick, firm strokes up and down the shaft, both of them unable to keep their eyes open as their bodies hitched and ached for release. Sherlock could feel the pressure building up in his abdomen, tighter and tighter, losing himself to the sensation, until the world shrunk down to a single point and he shouted John’s name brokenly before falling back onto the bed. Above him, John shouted too, but buried most of his cries in Sherlock’s shoulder, shuddering and then going slack, before carefully pulling himself out. He fell exhausted next to Sherlock, both lying there, vision dazed and blurred and their legs tangled together, waiting for their breathing to calm. After a few minutes, John wrapped an arm around Sherlock’s body, drawing him close into a warm embrace.

Sherlock mumbled something. He wanted to tell John how happy he was, how they would grow old together, exploring the wonders of the sea. But the words came out more like a faint hum, so instead they lay there, quietly humming a meaningless tune together, Sherlock’s deeper voice mixing with John’s lighter one. He drifted off to sleep at the sound of John’s breathing, the soft humming guiding him into a realm of peaceful dreams.

**Notes for the Chapter:**

> The ring Sherlock picked for himself is called a fede ring. The joined hands are meant to symbolise a union of marriage, most often popular for weddings or betrothals.   
> _Medhel an gwyns_ means “soft as the wind” and is a very beautifully romantic song which featured in the 2015 adaptation of Poldark. I imagine John’s ring originally belonged to a Welshman who was forced to fight in the war and lost his engagement ring when he was killed in battle, the ring simply tossed in with the rest of the looted treasure and only discovered again when Sherlock finds it several decades later.  
>  The language the men speak onboard is a mix of Polari and Sabir as mentioned in this chapter. Polari was a slang language used by sailors, theatre workers, and most notably gay communities in order to disguise conversation that otherwise would cause them to be discovered and arrested for illegal relationships. Sabir is a name for the Mediterranean lingua franca that existed for several centuries and was created for people all over the Mediterranean basin to communicate with each other while trading.


	5. Iceblink

**Notes for the Chapter:**

> I’d like to warn ahead of time that this chapter does include some descriptions of suffocation, in case this is triggering for some readers.   
> Wrap up warm for this chapter and enjoy! <3

Anderson had spent the last half of a year trapped in seventy meters of steel, wandering around the Atlantic Ocean in a seemingly destination-less manner, with only a rare sighting of a whale and barely anything to keep him busy between hunting trips. To say the journey was irritating would have been an understatement. He had been told a month in that he was technically free to leave any time he wanted to, but thanks to that bloody git of a professor insisting that he was going to stay, “free to leave” only meant “if you can swim several hundred leagues to the nearest continent”. 

Early on in the voyage, Anderson had discovered the certain nocturnal proclivities of the officers and crew which nearly made him take them up on that offer to swim to shore, but over time the amorous relationships between the men became surprisingly natural. He had hoped he would find Sherlock Holmes was, for all his peculiarities, a true gentlemen who did not partake of such activities, but after seeing the man flutter his eyelashes at the captain one too many times he had realised he was doomed to sail the ocean alone in this aspect.

So whenever the captain and Holmes staggered into the navigational room late the morning after “quiet night”, Anderson merely rolled his eyes and went back to helping Lestrade chart out their next destination. Now that they would be entering the Southern Ocean, he was being called in for his expertise in sailing through icefields, along with a few other men who had similar previous experience. Apparently the  _ Casse-cou _ had thus far only ventured through the Pacific Ocean, the Atlantic, the Indian, and the Mediterranean. How they managed to get from one ocean to the other was by all rational thought impossible ( _ “secret ‘Arabian Tunnel’, my arse!” _ Anderson had exclaimed), so this would be the first time they truly navigated the dangerous and tempestuous waters of the poles. 

“Gentleman, if I may have a moment of your attention,” Captain Watson announced, and Anderson tried very hard to ignore that the captain was holding Holmes’ hand, “As of today we are beginning a new part of this voyage. We will be the first ever to discover the South Pole!”

The officers seemed quite pleased at this idea, probably dreaming of glorious adventures, but Anderson had actually dealt with icefields before as a whaler and knew exactly what sort of dangers could lie ahead of them. Sod the rest of the crew and their glory, he wasn’t freezing to death in a metal matchbox.

“Beggin’ your pardon, captain, but I would heavily advise against that decision.” he said, and everyone looked at him, though none of them seemed terribly surprised that Anderson was the one objecting to the mission. 

“Have you much experience with polar expeditions, Mr. Anderson?” Captain Watson asked, slightly raising an eyebrow in that way he did when he was sizing people up to see if he’d missed anything the first time he judged them. 

As  Anderson briefly recounted some of his northerly travels, the captain said nothing and gave no indication of his thoughts.

When he finished, Watson frowned, then shook his head, “I appreciate your warning, Mr. Anderson. However I have talked with several others from my crew who have also had experience and they say the journey should be quite navigable. I’m sure with your expertise we should manage these waters quite well.”

It seemed that his word was the end of things, so Anderson groaned and resigned himself to making sure they came back out of the Southern Sea alive, while everybody else cheered and talked excitedly about what they might find. Yet when he looked back expecting to see Holmes gushing on about measuring new species, he found to his surprise that Holmes was instead glancing worriedly over at him, his fists clenched at his side. It seemed Anderson was not the only one who had worries of the coming month.

But why was Sherlock Holmes not using his relationship with the captain to turn the ship back around? Why did he look so worried, and yet so resigned to some unseen fate ahead?

\------------

Sherlock knew the exact moment when he realised he was going to die. 

He had been lying curled up next to John in their bed, rubbing fondly at his new ring and wishing he could stay wrapped up in their combined warmth for the rest of his life, when John had stirred awake and gotten up to put on his pants. 

“Where are you off to in a hurry?” Sherlock had asked with a morning-hoarse voice. John grinned at him, his eyes alight with excitement, and he reached over to pick up a book on his nightstand. It seemed fairly new, surely something that had been brought onboard during the past four years, perhaps by one of the crew. Flipping through the pages, Sherlock saw sketches of penguins and strange, large-toothed creatures. It wasn’t a very thick book, but it clearly contained knowledge about something new, something most people had never even dreamed of before.

“A vast ocean of islands of ice, floating all around the South Pole, with a great variety of new species to find and catalogue. No one has ever managed to reach the South Pole before… not until now.” John proudly announced. 

Sherlock hesitated for several moments, looking blankly at the sketches, “But why? What would you gain from being the first to reach the pole? No one would ever know but us.”

John leaned down and kissed him, “I don’t care about fame, love. I care about you. This would be the adventure of a lifetime; you could fill reams of paper with observations and knowledge, and discover all kinds of new phenomena.”

Sherlock looked up at John and saw this man, who would soon be his husband, standing proudly and holding a book he had managed to procure that spoke of lands unknown and adventures beyond imagining, and… and he didn’t have the heart to tell John otherwise. It did truly seem exciting, but exactly how much did John or his crew know about sailing through ice?

“Would you like that, Sherlock?” John asked, somewhat less confident now, his hand fidgeting at his side. But Sherlock smiled and kissing him back, nodding slowly and nuzzling against his cheek. John grinned again and went to go put on the rest of his clothes.

“By the way, where did you manage to get such a book?” Sherlock asked.

“Oh, I believe Moriarty brought it with him when he joined the crew. Donated it to the library as a token of thanks for letting him come with us.”

And that… that was when Sherlock realised he was going to die.

\------------

It was clear that Sherlock must have insulted Moriarty somehow during their first meeting, because after that Moriarty did everything possible to either avoid him completely or taunt him about being the odd one onboard. As wonderful as many of the officers were, it had always been clear that Sherlock was nothing like the crew. They found comfort in tall tales and ballads and whatever games they had invented to pass the hours. Sherlock, on the other hand, rarely left the library. And there was something else that separated him from Moriarty, something odd about the man he couldn’t quite put his finger on. 

That was, until the day Anderson caught a squid.

Anderson’s claims of fighting the shark in the underwater forest had earned him respect among even the most suspicious of crew members, but it was a title that he had to defend if he wanted to enjoy continued popularity. Ever since then, the man kept itching to go out and catch some giant monster of the deep. John humoured him by allowing him to go on the hunting trips with the others, while Sherlock was more than content after what happened the first time to simply enjoy the view from inside.

A week before they had landed near the treasure-bearing shipwreck, Anderson had gone off on a hunt as usual, and he caught a squid.

Not a gigantic beast, to be certain, but how he managed it no one seemed to know. The other men claimed he had used an entirely new electrical device to stun the squid so he could take it down without getting a limb ripped off. This of course caused quite a commotion on deck, with everyone insisting that Anderson reveal the device he had cleverly stored away in his hunting bag until then. What he drew out shocked them all. 

“How did you come by such a contraption, Mr. Anderson?” John demanded, his arms crossed against his chest, his normally smaller figure now a commandeering force. All eyes were on the whaler as he lightly tapped a trigger on the long, narrow harpoon. A small bolt of electricity flickered out down the barrel, bursting at the tip. The display briefly lit up the room with a pale blue glow, casting long shadows across the alarmed faces of the men.

“I can’t take credit for it, captain. That would be the honor of Mr. Moriarty. He’s been working on it for awhile; wanted to see if it would work so he gave it to me to try out since he can’t swim.”

“That is an unauthorised weapon.” John growled, raising his voice, “Mr. Moriarty? Is he in the room?”

“Here, sir.” a voice said from behind a wall of sailors. Moriarty stepped out into view, his head titled slightly like he was judging John, just as he had done when he’d first been introduced to Sherlock. “I apologise for not informing you, sir. Didn’t want to showcase my efforts only to have it fail upon demonstration. I assure you this poses no threat to humans. If it is treated like every other weapon on board with reasonable caution no one will be harmed.”

“But what  _ is _ it?” Sherlock asked. Some of the men appeared to be equally apprehensive, but many already seemed to be thinking about the captivating possibilities this new weapon could posses.

Moriarty took the electric harpoon from Anderson’s hands and held it up to the light bulb, sending a burst straight up to the bulb causing it to burst, throwing the room into darkness. The weapon glowed just enough for Sherlock to see Moriarty’s wide grin and piercing eyes. “It’s the future, Mr. Holmes.”

And then, just for a second, something caught Sherlock’s eye. As the glow from the weapon slowly began to fade out, he notices that the light splayed across Moriarty’s chest in a very peculiar way. In full light, as Sherlock had always seen Moriarty before, he had been too focused on avoiding the engineer to suspect anything. Yet here, in stark contrast, it was clear to him. 

Moriarty definitely had breasts.

\------------

The sun was still hidden beneath the horizon, but already the early morning sky was lighting up with pale pinks and purples and yellow. The Southern Sea had been surprisingly amiable to them thus far, especially since they were able to slip beneath the waves during storms. It had become a regular habit of Sherlock’s to go out whenever the submarine surfaced, wrapped warmly against the chilly winds. Today he had brought his sketchbook with him, as they were resting near an island of ice where several seals lay in perfect view. From his position, sitting on deck, he could draw somewhat accurate portrayals, and John had promised he could get measurements and proper anatomical data soon. 

“We should be heading into the Antarctic islands soon.” John said from behind him. Sherlock turned just as John settled down beside him, swinging his arm to wrap around him. John pointed towards the island of seals that Sherlock had been sketching, “Lestrade tells me this is Liverpool Island. The most remote place on the earth, according to him. Afraid it’s too tricky to land on, sorry about that. I’m sure we’ll have plenty of other opportunities to get a better look at them.”

Sherlock leaned his head to rest against John’s shoulder, closing his eyes, “Are we safe?”

“Hmm?” John shifted, “What do you mean, dear? We’ve had good sailing, and we can go below when it gets too rough. If I had any notion you would be in danger I wouldn’t dare continue.”

“It’s just…” Sherlock couldn’t say it. He’d been thinking about it, ever since he had found out Moriarty was most likely a woman. But clearly, whoever they were, Moriarty had almost complete control over the engine and much of the machinery that kept the  _ Casse-cou _ going. If he raised any doubt, outed her for any reason, he could not predict what Moriarty was capable of doing.

A warm hand cradled his cold cheek, bringing him to look over at John. His expression was concerned and serious, and he leaned close to Sherlock’s ear, “You can tell me anything, Sherlock. If we’re in danger, if you know something, I will gladly do whatever I need to keep you safe.”

“I… not here. Maybe later?” Sherlock offered, and John frowned but slowly nodded, pulling his husband into a warm hug. They sat there huddled together, quietly watching the sunrise for several minutes, before the hatch opened up and Lestrade appeared.

“Sir, we need your advice on some navigational issues. Anderson’s got something to tell you.”

“Yes, of course he does.” John grumbled, carefully making his way over to the hatch, “Get some of the crew to hack off the ice, will you? It’s starting to get slippery out here again.”

Their voices became muffled as they went down to the navigation room, and Sherlock rested on the deck, letting his thoughts drift off as he watched some of the seals dive into the ocean. A few minutes later, the hatch opened again and three crewmen came out on deck with ice picks, hacking away and avoiding where he sat for the time. When one of them got closer he went to get out of their way, but a firm hand clasped his shoulder and shoved him back down.

“How much did you tell him?” Moriarty asked in a low sing-song voice, “Mr. Holmes, how much did you say?”

“Nothing.” Sherlock sat absolutely still, looking out at the icy waters, “I didn’t tell him anything.”

“You don’t tell him. You hear me?” Moriarty pulled him closer, “You don’t tell Watson about who I am.”

“About you being female?” Sherlock guessed, and Moriarty chuckled.

“Slow. Oh, you are slower than I thought. No, he already knows I’m a woman, and I don’t think he cares.”

“And the harpoon?” a thought occurred to Sherlock and he gasped, “... the Magpie.”

The grip on his shoulder moved instantly to his throat, another hand clamping down over his mouth, “Whatever you know, whatever you think you might know, remember that I decide when and how the engines work and it would be a pity to cut this expedition short.”

Sherlocked gasped for air but otherwise tried to remain calm, still staring out at the island, now devoid of any seals. He couldn’t promise to never warn John or the rest of the crew about the danger they were in, so he stayed silent.

After a few moments, Moriarty released her grip on his mouth and throat, backing up, “I see, well, I’d better be off then. This deck is quite slippery, you could slip if you aren’t careful.”

Sherlock waited, then slowly stood up. He was about to turn around and head for the hatch when Moriarty deftly grabbed onto his coat and shoved him overboard into the water. Sherlock clamoured to get back to the surface but a patch of ice blocked him, and he struggled to find an opening. Up above, sounds of Moriarty and the two other crew shouting drew the attention of those below deck. He thought he could hear John with them too, ordering for a rope.

Darkness began to crowd around his vision and little sparks of light erupted in his head, panic dulling down to confused solitude, quietly watching those above rush around. A harpoon cut through the thin ice and speared down near to where he was. He feebly gripped onto it and the men above tugged hard, pulling him through the now broken ice until his shivering body lay on deck again. 

The next thing Sherlock recognised was a cocoon of slow warmth seeping into his bones as he lay wrapped up on his and John’s bed. Stamford sat on a chair nearby with a stethoscope hung around his neck. John, as Sherlock started to realise, was sitting in bed with him, letting Sherlock’s head rest in his lap as he tried to rub warmth into his husband’s still body.

“Mr. Holmes, how many fingers am I holding up?” Stamford asked.

Sherlock rolled his eyes, “Five, and you recently ate some of Angelo’s clam chowder soup, I assure you I’m fine.”

Stamford smirked, “He’ll recover. Certainly experienced no loss of sarcasm during the tumble.”

John nodded his thanks and ran his fingers through Sherlock’s hair as Stamford left them alone. His eyes were slightly red from trying to hold back tears, and his smile as lopsided when he cradled Sherlock’s head in his hands. 

“You were right.” he said, clearing his throat, “It’s not safe out there, for you or for anyone else. I should have listened to you a long time ago.”

“We were both wrong.” Sherlock mumbled, nuzzling into John’s arms.

“Can I have that on record? Sherlock Holmes, admitted he was wrong?” John grinned, and Sherlock ignored the tease, turning to look up at John.

“I have enjoyed most of the expedition. I’d still like to get some more notes on those seals, and I wouldn’t have traded those southern lights for anything.”

John smiled, absently rubbing at his ring as he remembered the night they got married, standing on deck with the southern lights stretching across the sky. It was true, that had been lovely, but after seeing Sherlock floating alarmingly still under the ice he had made up his mind on ending the expedition. He simply couldn’t risk lives because of curiosity.

“I’ve told Lestrade we’re going to turn back and head the way we came. We might see some more animals, and if we do I’ll try to get you as close to them as possible, but I can’t bear to see anybody else slip and end up less fortunate than you.” his body shivered and the familiar tremor awakened in his hand. Sherlock unraveled the blankets surrounding him and drew John into a hug, and they cuddled for most of the night, quietly comforting each other and feeling glad now that they had agreed to return to safer waters. 

\------------

_ He couldn’t breathe.  _

Sherlock sat up and stared into pitch black nothingness, his lungs aching and his chest heavy and throat tight. He couldn’t breathe and he wanted to scream, but instead he frantically tossed around trying to get his bearings, grasping at silk sheets and rolling roughly against what felt like a body lying next to him. 

He heard the sound of John’s voice, weak and thin, “What… what, dear god! Sherlock?” John started to cough, feeling around until he was holding Sherlock in his arms, taking deep breaths while pounding on Sherlock’s back.

“Breathe! Sherlock, breathe!” John dragged him off their bed until they clumsily bumped against the door, and he shoved it open, pulling Sherlock into the hallway where the air was not as thin. His body screamed at the sudden relief, his muscles sore and his brain pounding. 

From somewhere nearby, heavy footsteps rushed towards them, and Sherlock could tell from approximate height and weight that it was Lestrade.

“Captain! We’ve run in between two ice sheets and got trapped!”

“Then why did no one tell me? What the devil’s going on?” John asked hoarsely, still coughing. Even Lestrade seemed to be having difficulty getting enough air. He had wisely not lit any lamps except for the electric one he was now turning on, so as to avoid having any flames burn up the available oxygen.

“We just realised we were stuck about ten minutes ago. I thought we would be able to maneuver out but the ice had closed behind us so it looks like the only way out is forward.” Lestrade bowed his head, “Apologies, sir, it was my fault.”

“S’allright, Lestrade, let’s just try to escape as soon as possible. Find Moriarty and see what we can do with the engine, and rouse all of the crew. We’ll need as many men as possible to go out in the suits and try to chip away the ice.”

Lestrade rushed off towards the crew quarters, while John led a weakened Sherlock to the navigation room. Several officers were already there, hunched over the controls while a few were standing at the wheel, looking out in mute fear over the sight outside the window. It seemed they were situated in a narrow valley between two large chunks of ice, and while there was still a path ahead of them, the sides of the submarine has apparently gotten snagged. At the sight of their captain the officers breathed a sigh of relief and immediately started asking for solutions, and while John tried to sort out information from the worried men Sherlock lay down against an unoccupied section of wall, trying to get his breathing under control. 

For the next half hour some of the crew in suits risked the dangerous waters to hack away at the ice. Some of them had made progress, but a man arrived back early to report that some ice had grown around the back end of the ship. Even if they got rid of the ice at the sides, the back would take so much time ice would have grown back onto the sides once they finished.

“Damn it!” John cursed, his calm mask having dissolved long ago to reveal his temper. He kicked at the wheel and stood with his head down for several moments as some of the officers tried to suggest solutions. Sherlock had predicted this problem and had spent the last half hour directing all of his mental energy to calculating the least risky way out. He had to settle for the only way out, given their steadily decreasing amount of oxygen. He didn’t bother to stand up, knowing he was too weak for that, so he spoke as loud as he could manage.

“Boiling water.” he announced, and everyone turned to face him. He ignored their stares and continued, “If we can heat the engines up enough so that the propellers are warm as well, then this will melt the ice around the back. As the ice melts, and if we focus all our manpower to freeing up the sides, we could escape.”

“This would take an incredible amount of power, Mr. Holmes,” Moriarty said, while standing over a schematic of the submarine with a few other engineers.

“But can this be achieved?” Sherlock asked. 

“Yes, but we’d have to be out of the ice before the engines ran out of power. The engines are designed to work at a steady rate and certainly not at the temperatures you are suggesting.”

Everyone turned to John, who still had his head bowed. He glanced at Sherlock, still sitting on the floor and looking pale and struggling to breathe, and he knew he had no other choice. He stood up straight and nodded once, “Right, that’s what we’ll do then. All we need is enough engine power to melt the ice and then propel us to the surface where we can recharge and replenish the air. Any objections, speak now.”

No one spoke, and then as everyone else ran off to their posts or to suit up, John went to a back cabinet in the room and took out an extra oxygen tank, securing the mask to Sherlock’s mouth and nose. Sherlock tried to protest but John shook his head.

“Please keep this on, you clearly need this more than most of us. Please… for me?”

Sherlock grudgingly nodded and rested his head against the wall again, focusing on the air from the tank that was achingly pure compared to the rest of the submarine. He closed his eyes and listened, until eventually he could hear the sound of the engine roaring like a dragon awakened from slumber. Slowly, far too slowly, the submarine began to crawl forward, until the ship jostled free and suddenly rocked forward, throwing everyone onboard off their feet. When they got up again, the window showed they were finally moving, but nobody dared cheer before they were sure of their safety. 

Navigation through the ice valley was tricky even under the best conditions, but with an unknown limited amount of power left, it was clear John could not possibly risk snagging on any more pieces of ice. He stood at the wheel for almost ten minutes in complete silence while those not busy at the controls watched with wide eyes. 

Finally, just as some of the men were starting to have to sit down from lack of oxygen, the  _ Casse-cou _ broke through the surface. The engines puttered off and Lestrade flipped on the switch to open the hatches and draw in fresh air. 

John let go of the wheel with a wince, his palm rubbed raw and nearly frozen into fists, and when he kneeled down to gently take Sherlock’s mask off he did not bother to hide the tears streaming down his face.

**Notes for the Chapter:**

> The “Arabian Tunnel” is a canon reference to a secret tunnel that the Nautilus swims through to get from the Indian Ocean to the Mediterranean. Purely fictional and put there so Verne could avoid having to send the Nautilus all the way around the South African tip to get to the Atlantic. Anderson is not so convinced of its existence.   
> John mistakenly believes that Antarctica is just a sea of islands, not one huge continent. To be fair though, most explorers before him spotted the continent and thought it was just an island too.   
> Liverpool Island is a historically nerdy reference to Bouvet Island, but it was named “Liverpool” at the time the Casse-cou would have stumbled across it. And it is indeed considered to be the most remote place on the earth, just barely outside the Antarctic Circle and nowhere near land on any side. Unfortunately for everybody onboard there are plenty of icebergs near it.  
> \---------------
> 
> Thank you for reading! Please leave a comment if you enjoyed this, I love hearing from you!  
> Or you could always follow me on [Tumblr](thebisonwitheadphones.tumblr.com).


End file.
